if the motor sounds like it is working, but the window doesn't move, it is the regulator. My right rear window has this problem and the window is stuck up. I never use it, so no big deal. My local bmw shop wants $50 just to open the panel and have a look. Anyone out there who has a diy guide to fixing regulators would be helping this gentleman and myself. How to open the door panel without making a mess, etc. I have also been told that you must open and close the windows just to keep the moving parts moving or the regulators dry out and stop functioning.