power window problems

i roll down my driver side window and try to roll it up
nothing happens. i have to hold the switch and beat the
bottom of the door to get it to roll up. what could cause this?

I had/have the exact same problem... I took the door apart, checked all the wiring on a voltmeter, and everything was wired fine - no shorts. I figured that it was the motor. I put the door back on and without replacing the motor, the window started working again. I have no clue what happened, or how it started working again.

Now, The passenger side window is doing the same thing. I don't want to rip it all apart again if the same thing is going to happen.

hmmm...