A fairly easy DIY job to replace the assembly. There is no repair possible. Rewinding it with the hex key may buy you some time but total failure is inevitable. Only source I can find for the part is Ford. The part alone will probably cost $250.00 to $300.00 or more. Ridiculous to pay dealer to replace it, unless you are physically unable. Remove all interior molding around the door from the dash back to and including the interior side panel. This will involve removing the rear seat and probably the rear speaker covers as well to get to all the attachment points. The entire assembly unbolts from the frame and attaches the same way. There are about 7 bolts attaching the guide rail around the door, and a few more on the side frame behind the door. You have to replace the motor, cable, and guide rail -- all one single unit.
Allan, May 2007