Yesterday afternoon I lost all function in my drivers side window. It would not go up or down and was stuck in the down position. It was a rough night with the car parked on the street with the window down.
Today I called around and found a motor. I took the door apart and found something rather interesting. The motor rivots had come loose and the motor was held on by only one of them. I pushed the motor back in to place and it worked to raise the window. So instead of needing a new motor, I got away with just drilling out all of the rivots and replacing them with short pan head screws.
NOW, what I did find is that after everything was back together it seemed to me that the gear mesh was WAY TOO TIGHT. So I adjusted it a little. just enough to back the raising mechanism away from the gear on the motor. I also lubed it up real well. I now have a window that screams up and down. I mean even with the old motor it raises and lowers at twice the speed it did before.
Tomorrow I will take the passanger side apart and do the same adjustment over there. It appears that the factory gear mesh may just put too much strain on the motor and that is what burns them out and makes them so darn slow.
Just an FYI.

 

hmm..i need to try this on my brothers Z24