So your power tool is running intermittently. One moment it’s working fine, just like it always did, and the next it’s completely dead. Click the trigger a few times and it’s running again. What in the world is going on?
While there are many problems which can cause intermittent power tool operation, the two most common failures are the switch and the brushes. You’re probably already familiar with these parts. The switch usually sits behind the main trigger, controlling power flow from the wall to the tool. The carbon brushes actually transfer power to the tool’s motor. It can be difficult to determine which failure you’re experiencing because both the brushes and the switch deal with electrical connections within the tool.
But you’re not out of luck. There are clues which can help you find the problem.
When a switch is worn out it works more and more infrequently. At first it works pretty much all the time and occasionally it has to be clicked twice to start the tool. Over time, you might find yourself clicking the switch several times every time you start the tool. Of course, once the tool is running it works perfectly as long as you hold down the trigger. Problems of this sort are textbook switch malfunctions. Don’t throw that power tool away! You probably just need a new switch.
Brushes problems are a little different. When brushes are becoming marginal sometimes a power tool will begin to “cut out” while it’s running. Sometimes you might tap or slap the tool to get it running again. The trigger starts the tool just fine, but it doesn’t run well. This sort of symptom usually points to a brush problem. You will want to inspect your brushes before replacing them. A worn out brush will often have a small amount of carbon remaining, or it will be pitted or chipped. If your brushes are bad, it sometimes means that your power tool has bigger problems (like a worn out motor), but often a fresh pair of brushes can get everything working again.
Of course there are lots of things that can go wrong with a power tool, and any repair should be approached with caution and ample troubleshooting. If you feel unable to repair the tool, there are lots of power tool repair shops which can do the job for you.