DIAGNOSIS Sawdust and drywall dust are blocking the motor cooling vents on the gear housing. This causes overheating and premature failure.
FIX Unplug the battery. Use compressed air from a can or compressor. Blow air directly into the long vertical vent slots near the motor. Angle the air flow to push debris out the back of the tool. Do not use liquids.
IF THAT DIDN'T WORK For packed dust, use a soft, dry brush (like a paintbrush) to loosen it first, then use the air. Do not insert metal objects into the vents.
HEADS UP Never submerge or spray cleaner into the vents. The motor and electronics are not sealed. Moisture will cause a short and permanent damage.