The worm screw on my power window motor screws in so far that it tightens up, causing the window to stick in the down position. When I take the cover off the window motor I can unscrew the worm gear, freeing up the window. What is causing this and are there any fixes short of replacement. Thanks.

 

There are "down stops" that limit the distance the window moves down. There are invariably adjustments for these. It's usually a screw that you turn and lock with a nut. Yours may have gotten out of whack somehow. Look for it, and set it so the window doesn't go so far as to jam the motor.