Passenger Window stuck- 1982 380SL - Help

[wisard]

First, thanks to all for the "great" past information I have been able to get.
Special thanks to "Ray" for all his help. She is still running well but needs some more work.

Problem: this morning I rolled up the passenger window and now it will not roll down - I can hear the motor running but the glass does not budge. Is this an "easy" fix? is it costly ($$ ha ha) if I need to replace the lifter and... once the panel is off is it difficult to replace the door locking mechanizm? (the guy I puchased the car from tried to fix it and took the parts out but could not put the parts back).