Thank you for the other sources.

Any electrical engineers out there?
Before I consider a "new" memory computer board or something more radical... here are the facts:
2000 my 996 Carrera 4 Cabriolet (US model)
1. All seat motors work when given direct current to their female plugs - both in
forward and reverse modes.
2. I connected all 3 sources of power from the cars electrical system to
the memory computer (# 6 and #7... and the monster one to the seat
wiring harness). Main fuses ok. Grounds looks very clean and good.
Then I connected # 9 seat switch control plug to the memory computer
(white,blue,black).
There is only power at the centre small male "plugs" on #1, #2/3, #2/3, #4
(right to left on the memory computer) when seat control switches are
engaged, but consistent power to # 8, 9, 10 (larger spade types) without
touching seat controls. Connecting each seat motor connector to the memory
computer does not engage seats.
3. I do not see any fuse that I am familar with inside the memory computer.
4. There are definitely relays being tripped on the seat memory board when seat
control switches are engaged and when I checked for power at # 1, 2/3, 2/3, 4 with a circuit tester.