Power window (driver's door) stopped working. Pushing the button caused the lights to dim, so I purchased a new motor from CarQuest. In the midst of replacing the motor, the window worked again. I put Humpty Dumpty back together without replacing the motor (which includes removing the whole regulator system and is a PITA). Naturally the window operation failed again later, but is itermittent, and I can't identify a unique circumstance that isolates the problem. I know it won't fix itself, but I'm at a loss as to what is the problem. Does anyone have any advice on how to diagnose the problem before replacing the motor in hopes that solves the problem? The other three windows work fine from both the drivers' door and the individual door buttons. It seems to be a driver's door issue for the driver door window only.

Kevin