question about power windows

[L92 OLDS]

The window motor does not ground through the door.it gets power and ground from the switch.the switch reverses the polarity depending on wich way you want to go.

Bangin on the bottom of the door will rattle the motor out of a dead spot,replace motor.

Bad switch,itll usualy go one way or the other.

Broken wire in door jam,it wont do anything in either direction.

That is correct ^^^^
The motors get gummed up and stop working intermittently. Banging the door likely completes the circuit inside the motor. I've often seen root cause being the brushes binding up or week spring pressure due to dirt and hard grease. The motors are serviceable and can be opened up, cleaned and repaired without special tools. Tabs on the motor case keep the motor housing assembled. Take your time and have fun with it.

 

[69hurstolds]

My vote is the switch is going bad, or the pins on the back of the switch need cleaning. OR- as Anubis said about the gummy motors.

Can't ever rule out an electrical/wiring problem, but in my experiences, the wiring isn't usually the issue with the windows. Although I have had to replace one of the wire clips on the back of the switch plug one time.