cskewis,
The answer to your question is in the other threads you posted in. Specifically, post 13 on this thread shows the current path:
http://forums.pelicanparts.com/porsche-911-technical-forum/621142-1986-911-power-windows-sunroof-stopped-working.html
Power for the Power Window Control Unit (PWCU) comes from the ignition switch in the ACC and RUN position through a bulkhead connector to the Unit. Main power from the 30 bus (always energized buss located on the top of the fuse block between fuses 4 and 5 from the left a red/black wire) also goes to the PWCU and is the main power supply for the power window motors. That power comes back out of the PWCU as that black wire to the top of the fuse.
So you need to check for voltage into the PWCU position 7 with key in ACC and RUN position, check for voltage into the PWCU position 2 at all times, and check for voltage out of the PWCU at position 14 when operating the window with key in ACC or RUN. A faulty PWCU can cause your problem.