before condemning the regulator or the motor, check the plastic clip that goes through the holes in the glass and has a metal nut/screw holding the glass part to the metal parts - in many instances, the plastic look like it is really in good shape while in reality it had partially disintegrated and thus putting additional stress onto the mechanics of the lift as the geometry is now skewed...

it is a $2 part that will cost you regulator and even motor - there are 2 of them in the front of the car...

do a search on this forum, you will find the part number, and pictures of the part...