What is it that makes your starter work when you bang it with a hammer? I've long done this on my 4-wheelers, etc but never really knew why. I was just reading a post on here where someone told a guy to carry a hammer in case it needed a whack. Just wondering, I've never opened up a starter so I don't know...

 

Sometimes the solenoid will stick and the vibrations from a moderate tap can loosen it up. This is generally a sign that the solenoid is going to give up soon.