Power Window is Slow
After you remove the motor check the to see if the winding is still intact which it sill probably be, as the problem will probably be the overload (?) switch. You can get at this by removing the end of the motor and in it you will find a small thin black rectangle (about 1.5cm wide x 0.5cm deep x 2cm high) in the motor end base that you remove. It has two soldered lugs on it.
The power actually comes from the wiring through the overload to the motor, on one side and directly to the motor on the other. I found with mine that inside this rectangle is a bi-metalic strip (N.C.) that goes open when heated (overloaded) when the window jams or is obstructed. Mine has corroded causing the strip to seperate from the contacts where it had been spot (RF ?) welded to them. I would suggest replacing this with a automatic resetting circuit breaker of the appropriate rating - any one know the correct rating ? inside the door.
Hope this helps,
'84 928S Euro (Australian Delivered down under)
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