the trigger on my milwaukee m18 drill driver feels sticky and sometimes doesn't work, can i fix it?

Diagnosis

The sticky trigger on the Milwaukee M18 2801-20 is typically caused by one of two things: external contaminant ingress or internal spring fatigue. Because this is a jobsite tool, fine sawdust, drywall dust, or metallic shavings often migrate past the trigger housing. These particles mix with the factory lubricant to create a gritty paste that increases friction against the trigger pivot points, preventing the switch from fully engaging the contacts. If the trigger doesn't just feel sticky but intermittently fails to activate the motor, the issue is likely a worn-out contact point or a misalignment in the trigger assembly's plastic guide. When the trigger is pulled, it compresses a spring-loaded switch; if debris is lodged in the gap between the trigger blade and the housing, the switch won't be fully depressed, leading to "dead spots" where the drill refuses to spin despite the trigger being pulled.

How to Fix It

If your tool is out of warranty and you are comfortable with basic disassembly, you can perform a deep clean and lubrication of the trigger mechanism. You will need a T10 Torx driver and a can of electronic-grade contact cleaner.

1. Remove the battery pack and ensure the tool is completely powered down.
2. Using a T10 Torx driver, remove the housing screws. Be careful with the screws near the base of the handle, as they often vary slightly in length; keep them organized.
3. Carefully pry the two halves of the plastic clamshell housing apart. Avoid jerking the shells, as you may snag the wiring connecting the trigger switch to the motor.
4. Locate the trigger assembly. Use a pressurized can of non-conductive electronic contact cleaner to blast out all debris from the trigger pivot and the internal switch housing. Spray liberally until the liquid runs clear.
5. Manually cycle the trigger 20-30 times while the cleaner is still wet to flush out any remaining grit.
6. Apply a tiny amount of high-quality synthetic lithium grease to the external pivot pin of the trigger. Do not apply grease directly to the electrical contacts of the switch.
7. Reassemble the housing, ensuring the wires are tucked into their molded channels to avoid pinching them during closure.
8. Tighten the T10 screws firmly, but do not over-torque them, as the plastic housing can strip easily.

If That Didn't Work

• Replace the Trigger Switch Assembly: If cleaning fails, the internal diaphragm of the variable speed switch has likely failed. You will need to order a replacement trigger switch assembly specifically for the 2801-20 model. This requires disconnecting the two primary power leads and transferring them to the new switch.
• Inspect the Trigger Spring: Check the return spring located behind the trigger blade. If the spring has lost its tension or is kinked, the trigger will not "snap back" into place, causing a sticky feeling. Replace the spring with one of identical gauge and length to restore the tactile response.
• Check for Housing Warp: Inspect the interior of the plastic casing for any cracks or warping. If the tool was dropped, the housing may be pinching the trigger. You can lightly sand the interior contact point where the trigger rubs against the shell to create more clearance.
• Professional Warranty Claim: If the tool is still within the five-year limited warranty period, stop DIY attempts immediately. Contact a Milwaukee Service Center and provide your proof of purchase. They will replace the entire trigger module and recalibrate the motor controller.

Heads Up

• Avoid using WD-40 Multi-Use Product inside the trigger housing; it can degrade the plastic and attract more dust, making the stickiness worse over time. Use only dedicated electronic contact cleaners.
• Always verify that the trigger is fully returning to the "off" position before inserting the battery. A stuck trigger can cause the tool to "ghost start" the moment the battery is clicked in, which is a significant safety hazard.
• Periodically use compressed air to blow out the trigger gaps every few weeks if you work in high-dust environments like demolition or woodworking.
• Ensure you use the correct T10 Torx bit. Using a flat-head or an ill-fitting bit will strip the screw heads, making it nearly impossible to open the tool for future repairs.