In your recent posting about the electric window switches, I've had similar
troubles with my '87 5000CQ (=100 Quattro?). It was fixed by removing the
various switches from the various consoles, carefully prying off the switch
covers, removing a cellophane like covering, and spraying liberally with a
contact cleaner (and carefully reassembling). Since that time I have had
trouble with the passanger side window, where it would go down from either
the individual or the master console switch, but would not go up for either.
That has been consistantly responsive to manipulating the wiring harness
that plugs into the underside of the switch for the passanger window in the
master console - never had to mess with the passanger switch. I recently
pulled the harness off of the connectors, cleaned them and the harness
connector with contact cleaner, and have gone a few weeks without recurrance.
I'm not sure that the switches will be the same in your car...