Quote from Haasman:
"It has been reported that the wires that run through the flexible conduit break. I believe you can pull it off at the door jam to check them."
I could not agree more. About 6 months ago my rear passenger window stopped working out of the blue, I checked the wires at the conduit and 'voila' wire broken, fixed problem.
About a month ago, my drivers side rear window stopped working, I haven't gotten around to check it yet, the fuses look good, I am pretty sure it is the wire.

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
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