Slot Machine Maintenance: A Homeowner's Guide

A slot machine is a mechanical and electronic device with moving parts, electrical connections, and components that wear over time. The good news is that home machines see a tiny fraction of the use they received on a casino floor. A casino machine might get 8 to 12 hours of continuous play daily. Your home machine might see 2 to 5 hours per week. That dramatically extends the life of every component.

But low use does not mean no maintenance. Dust accumulates. Lubricants dry out. Batteries drain. Connections oxidize. A few minutes of preventive maintenance each month keeps your machine reliable and extends its life by many years.

After 33 years of servicing and refurbishing slot machines, we have distilled everything into a practical maintenance schedule any homeowner can follow. No special training required. Just basic tools, some common supplies, and a willingness to open up the machine occasionally.

Tools and Supplies You Will Need

Before we get into the schedule, gather these items. You probably have most of them already.

• Phillips head screwdriver (medium size)
• Compressed air cans (the kind for cleaning electronics)
• Isopropyl alcohol (90% or higher, not the 70% stuff)
• Lint-free cloths or microfiber towels
• Cotton swabs
• A small vacuum with a brush attachment
• Glass cleaner (ammonia-free for monitors)
• Light machine oil or white lithium grease (small tube)
• Your machine keys (main door key, top box key, service key)

Do not use household cleaning sprays, furniture polish, or any petroleum-based solvents on your machine. These can damage plastics, acrylics, and electronic components.

Monthly Maintenance (15 Minutes)

These tasks should be done once per month regardless of how often you use the machine. Set a recurring reminder and knock these out. Fifteen minutes once a month prevents expensive repairs.

Exterior Wipe-Down

Using a slightly damp microfiber cloth, wipe down all exterior surfaces. The button panel, the glass front, the top box glass, the coin tray, and the cabinet sides. This removes dust, fingerprints, and any sticky residue from spilled drinks (it happens).

For the glass panels, use ammonia-free glass cleaner sprayed onto the cloth, not directly onto the glass. Liquid sprayed directly can seep behind the glass and damage backlighting or printed graphics on the reverse side.

Button Panel Check

Press each button on the machine and verify it responds correctly. Check the spin button, the bet buttons, the cash-out button, and any other player-facing buttons. They should feel responsive with a positive click. If any button feels mushy or requires extra pressure, it may need cleaning or the microswitch behind it may be wearing out.

Listen for Unusual Sounds

Power the machine on and just listen during normal operation. You should hear the normal sounds: fan humming quietly, reels spinning (on mechanical machines), or the speaker playing normal game sounds. Any new sounds like grinding, clicking, buzzing, or rattling indicate something needs attention.

Check the Power Cord and Surge Protector

Glance at the power cord where it connects to the machine and where it connects to the surge protector. Look for any fraying, kinks, or discoloration (which indicates heat). Verify the surge protector's indicator light still shows active protection. Surge protectors wear out over time and stop protecting even while still passing power. Replace them every 3 to 5 years.

Quarterly Maintenance (30-45 Minutes)

Every three months, do the monthly tasks plus these additional items.

Interior Dusting

Open the main door and use compressed air to blow out dust from the interior components. Focus on the power supply (dust buildup causes overheating), the main logic board area, the fan and its intake/exhaust vents, and any circuit boards visible inside.

Hold the compressed air can upright to avoid spraying liquid propellant onto components. Use short bursts rather than continuous spray. Work from top to bottom so dust falls downward and out.

If dust accumulation is heavy (which indicates your game room needs better filtration or more frequent cleaning), use the small vacuum with brush attachment first to remove the bulk, then follow with compressed air for the tight spots.

Bill Acceptor Cleaning

The bill acceptor is the single most common source of problems in home slot machines. It has optical sensors, rubber transport rollers, and a mechanical stacking mechanism. All of these collect dust, paper lint, and residue that eventually cause jams and read failures.

Here is how to clean it properly.

Open the bill acceptor head (it usually hinges forward after pressing a release tab). You will see the transport rollers and the optical sensors.

Clean the rollers with a cotton swab dampened with isopropyl alcohol. Roll each roller with your finger while wiping to clean the entire surface. These rollers are what grip and feed bills into the machine. When they get glazed with residue, bills slip and jam.

Clean the optical sensors with a dry cotton swab or a swab lightly dampened with alcohol. These are the small glass or plastic lenses visible in the bill path. There are usually 2 to 4 pairs of sensors. Any dust or residue on these causes the acceptor to reject valid bills or misread denominations.

Blow out the entire bill path with compressed air to remove paper dust and debris.

Reassemble the bill acceptor head and test with a few bills of different denominations to verify proper operation.

If your machine is set to free play and you never use the bill acceptor, you can skip this cleaning. But if you ever want to switch to bill play, you will want a clean acceptor ready to go.

Hopper Inspection (Coin Machines Only)

If your machine uses coins, the hopper is the bowl-shaped mechanism inside the bottom of the cabinet that stores and dispenses coins. Once a quarter, check the following.

Open the main door and locate the hopper. Look inside for any foreign objects (paper clips, broken coin blanks, or debris). Remove anything that should not be there.

Check that the hopper sits securely in its mounting position. Some hoppers sit in a cradle and can shift during enthusiastic play sessions where the machine gets bumped.

Manually rotate the hopper dispensing disk (the flat disk at the bottom with coin-sized notches). It should rotate freely without binding. If it feels gritty or stiff, remove the hopper and clean the disk area with compressed air and a dry cloth.

Verify the hopper electrical connector is fully seated. A loose connector causes coin-out failures and tilt errors.

Fan Cleaning

The power supply fan and any case fans accumulate dust on the blades over time, reducing airflow and eventually causing the fan motor to strain. Remove dust from fan blades with compressed air or a cotton swab. If a fan is noticeably louder than when the machine was new, or if it wobbles visibly, it should be replaced. Replacement fans are inexpensive, usually $10 to $20, and are a standard size available at electronics suppliers.

Semi-Annual Maintenance (60-90 Minutes)

Twice a year, do all the above plus these deeper tasks.

Connection Check

Open the main door and visually inspect all cable connections you can see. Gently push each connector to verify it is fully seated. Vibration from the hopper motor, from speaker bass, and from excited players hitting buttons can slowly work connectors loose over months.

Pay particular attention to the edge connectors on the main logic board. These flat ribbon-cable style connections are prone to working loose. Push them firmly into their sockets.

Reel Maintenance (Mechanical Reel Machines)

If you have an IGT S2000, S-Plus, or similar mechanical reel machine, the reels benefit from semi-annual attention.

Open the top of the machine and look at the reel assembly. Check that each reel spins freely by gently rotating it with your finger (with the machine powered off). They should spin smoothly without catching or grinding.

Look at the reel strips (the printed strips with the symbols). Check for any peeling at the edges or tears. Damaged reel strips affect gameplay and should be replaced.

Check the reel stop mechanisms. Each reel has a stepper motor that positions it precisely. Listen during play for any grinding or clicking that was not there before.

Monitor Care

Your machine's monitor is either a CRT (older cathode ray tube) or an LCD (flat panel). Each has different maintenance needs.

For CRT monitors, check for any degradation in brightness or color. CRTs dim over time as the phosphors age. A CRT that has become noticeably dim or has developed a color tint (often reddish or greenish) is approaching end of life. There is no maintenance that reverses this; the tube eventually needs replacement, and we recommend an LCD conversion at that point.

For LCD monitors, check for any dead pixels, bright spots, or uneven backlighting. Clean the screen surface with an ammonia-free LCD cleaner and a microfiber cloth. Never press hard on an LCD panel. Never use paper towels as they can scratch the coating.

Regardless of monitor type, check that the mounting hardware is secure. The monitor sits in a bracket inside the cabinet, and vibration can loosen the bolts over many months.

Touchscreen Calibration (Video Machines with Touchscreens)

If your video machine has a touchscreen, verify calibration by touching each corner of the screen and confirming the machine registers the touch in the correct location. If touches are registering in slightly wrong positions, you need to recalibrate. This is usually done through the operator menu under a "touchscreen" or "display" section. The calibration process asks you to touch a series of targets on screen, similar to calibrating a tablet.

Also clean the touchscreen surface with appropriate cleaner. Touchscreens work by detecting finger contact, and a dirty surface can cause missed touches or phantom activations.

Annual Maintenance

Once a year, do everything above plus these critical annual tasks.

Battery Check and Replacement

This is the single most important annual task. Every slot machine has at least one battery that maintains critical memory when the machine is powered off. When this battery dies, the machine loses its settings, its accounting data, and potentially the game software itself.

On IGT machines (S2000, S-Plus, Game King, and most others), the critical battery is a Dallas DS1287 real-time clock module. This is not a standard battery you can buy at the drug store. It is a specialized integrated circuit with an internal lithium cell. It is soldered onto the main logic board or plugged into a socket depending on the board revision.

The Dallas DS1287 has a typical lifespan of 7 to 10 years. If your machine is refurbished and we installed a new one, you have years of life ahead. But if you bought a used machine or it has been more than 5 years since the last replacement, check the date on the module.

When this battery gets low, the machine may show a "low battery" error code on startup. Do not ignore this. Once the battery dies completely, the machine will lose all RAM data. On some platforms this means a complete reconfiguration from scratch. On others it means you need new EPROM chips reprogrammed. Either way, it is expensive and avoidable.

On Bally machines, the backup battery is typically a standard 3.6V lithium cell that is easier to source and replace. On WMS machines, it varies by platform.

If you are uncomfortable replacing batteries yourself, this is a good time to contact us for guidance. We can walk you through it over the phone for your specific machine model, or sell you the correct replacement part.

Power Supply Load Test

The power supply converts household AC power to the various DC voltages the machine needs (typically +5V, +12V, and +24V). Over years of use, power supply capacitors age and voltage regulation can drift.

If you have a multimeter (even a cheap one works), check the DC output voltages at the test points on the power supply board (if labeled) or at the connector going to the main board. The +5V rail should read between 4.9V and 5.1V. The +12V rail should read between 11.8V and 12.2V. If any voltage is more than 5% off specification, the power supply should be replaced.

If you do not have a multimeter or are not comfortable with this, skip it and just monitor for symptoms of power supply degradation: random resets, display flickering, or intermittent errors that clear on their own.

Door Switch and Security Check

Verify that all door switches function correctly. When you open the main door, the machine should register a "door open" condition (usually shown on the display or heard as an alert tone). When you close the door, it should clear. Same for the top box door and the coin door if applicable.

These switches are a safety feature. In a casino they trigger security alerts. In your home they simply ensure the machine knows its doors are properly closed, which matters because some machines will not operate with a door registered as open.

When to Call a Tech

Some problems are beyond basic home maintenance. Call for professional help if you encounter any of the following.

• The machine will not power on at all and you have verified the outlet has power
• The monitor displays a solid color or horizontal/vertical lines
• You smell burning or see smoke (unplug immediately)
• The machine shows persistent error codes that do not clear after a power cycle
• Mechanical reels do not spin or stop in wrong positions consistently
• The main logic board shows visible damage like burnt components or leaking capacitors
• You need to replace the Dallas DS1287 battery and are not comfortable soldering

If you purchased your machine from us, call our tech support line first. We resolve the majority of issues over the phone with our customers, and when parts are needed, we can ship them quickly with instructions.

Common Maintenance Mistakes to Avoid

After decades of seeing what customers do to their machines, here are the mistakes we see most often.

Using WD-40 on Everything

WD-40 is not a lubricant. It is a water displacement spray that leaves a residue attracting dust and grime. Do not spray it on reel mechanisms, coin mechanisms, or any internal components. Use proper light machine oil (a single drop where needed) or white lithium grease for mechanisms that need lubrication.

Over-Cleaning with Harsh Chemicals

Bleach, ammonia-based cleaners, acetone, and harsh degreasers destroy plastics, strip printed graphics, and corrode metal contacts. Stick with isopropyl alcohol for electronics and mild soapy water (well wrung out) for exterior cabinet surfaces.

Ignoring the Bill Acceptor Until It Fails

The bill acceptor gives you warning signs before it fails completely. It starts rejecting bills it used to accept. It becomes picky about bill condition. It takes multiple attempts to feed a bill. These are signs it needs cleaning. Do not wait until it stops working entirely.

Running Without a Surge Protector

We see this constantly. Someone sets up the machine perfectly with a surge protector, then rearranges the game room six months later and plugs the machine directly into the wall because the surge protector does not reach. Then a power surge kills the logic board. A $400 to $800 repair bill because of a $40 item.

Never Opening the Cabinet

Some owners treat the machine like a sealed appliance and never open it. Dust builds up for years. Connections slowly loosen. A battery dies and nobody notices until the machine loses all its settings. Opening the cabinet quarterly for inspection and cleaning prevents all of these scenarios.

Using Coins from Unknown Sources

If you run a coin-operated machine, use only standard US coins of the correct denomination. Foreign coins, arcade tokens, and worn or damaged coins cause jams, damage the coin comparator mechanism, and can trigger tilt conditions that lock the machine.

Leaving the Machine Powered On 24/7

Unlike casino machines that run continuously, home machines should be powered off when not in use. This extends the life of the monitor (especially CRTs), reduces wear on the power supply, and lowers your electricity bill. The boot-up sequence only takes 30 to 90 seconds, so there is no practical reason to leave it running all the time.

Seasonal Considerations

If your machine is in a room that experiences temperature or humidity changes with the seasons, take extra care.

In winter, if the room where your machine lives gets very dry from heating, static electricity becomes a concern. Static discharge can damage sensitive electronics. Consider a small humidifier in the room if you notice frequent static shocks.

In summer, if the room gets warm, ensure the machine's ventilation is not obstructed. Slot machines are designed to operate in casino environments (typically 68 to 72 degrees Fahrenheit). They can handle warmer temps up to about 85 degrees, but prolonged heat shortens component life.

If you lose power for an extended period (days), the machine will be fine. The backup battery maintains critical memory. When power returns, just turn it on normally. If the power was out for weeks and the room experienced extreme temperatures, follow the temperature acclimation protocol (let the machine reach room temp for several hours before powering on).

Maintenance Log

Keep a simple written log of your maintenance activities and any issues you notice. This sounds old-fashioned but it is genuinely useful. Note the date, what you did, and anything that seemed different or concerning. This history helps if you ever need to troubleshoot a problem or if you eventually call for technical support. We can diagnose issues much faster when the owner can tell us when something first started versus discovering it only today.

A simple notebook kept near the machine works perfectly. Date, task, notes. Takes 30 seconds to jot down after each maintenance session.

The Bottom Line

Slot machine maintenance is not complicated or time-consuming. Fifteen minutes monthly, 45 minutes quarterly, and one focused session annually is all it takes to keep your machine running reliably for 10, 15, even 20 or more years.

The machines we refurbish and sell were often running on casino floors for a decade or more before coming to us. With proper home maintenance at a fraction of the use intensity, there is no reason your machine will not provide entertainment for the rest of your life.

And remember, we are always here to help. Free lifetime tech support means exactly that. Call us anytime with questions about maintaining your machine. We have been keeping these machines running since 1992 and we have seen it all.