Thanks Benzmac, that is what I suspected.
Until the part gets here, I guess I will try the old "screwdriver in the track" trick. It won't be the first time - the '73 280 (euro lamps) I had in college had the driver's window regulator fail. Funny how cars from the same maker have the same peculiarities.
Say, the fastlane is offline right now - do you happen to know that part number?