85 380SE - the driver's side window makes a thumping noise when it's raised and a loud banging noise when it reaches the top of the track. The motor doesn't seem to stop when it's raised all the way. Is this the motor or is it off track? It seems to be slipping on the way up but it lowers with no problem.

It sounds like the regulator is missing a few teeth. The best way to tell is to take it apart and have a look at it. The reason it goes down smoothly is that it's spring loaded to help it lower quickly. On the way up, the motor has to overcome the spring tension. I'll bet the last couple of teeth on the regulator are worn out. Make sure you look at the gear on the motor as well. Good luck

Thanks for the response? What would a regulator cost to replace - any idea?

they're not too expensive, around $90 if you don't need the motor with it

you can order one from fastlane for ~$85 or so

__________________
Own:
2013 C300 4matic
2009 C300 4matic

Owned:
2001 E320 Sport
1992 500E
1989 300SEL