So I've got this '00 Grand Prix GTP (two-door) that I picked up as sort of a project to try to make some money off of. I know it's not a Chevy, but I imagine most GMs use the same or similar power setup. It's nearly finished and the driver's side power window decided to start misbehaving. It gets stuck down; when I hit the button to raise it, it'll go a few inches (so I know it's getting power), but then stop and won't go up or down from there. Sometimes, if I wait a while, I can get it to go up another inch or two, or maybe come back down.

I took the motor out and it still spun (just slowly) when I pushed the button while it was detached from the regulator. I put it back on the regulator to see if I could get it to wind up the window and it went a few inches and stopped again. When I detached the motor again, it wouldn't spin at all anymore.

I figured the motor was going bad, so I picked up another one from the junkyard that seemed to spin much better. It wound the window up all the way (just a little slowly) and back down with no trouble, but when I tried to roll it back up again, it got stuck about halfway up. Now the motor is behaving pretty much the same as the old one.

Before I went through the trouble of exchanging my junkyard motor for another one, I just wanted to ask you guys if this sounds more like the motors were both bad or if maybe there's a problem with the regulator that's put too much strain on the motors and caused them to stop working (I don't know, maybe from overheating or something).

What do you think?