1989 Volvo Turbo 760: electric seat control on the driver's seat broken

Hi All,

One of the electric seat control on the driver's seat of my 1989 Volvo
Turbo 760 broke in a very inconvenient way.

A few days ago, something that fell down accidentally touched the
control that moves the driver's seat back and forward,
the big fat control in the center of this image:

http://lternet.lternet.edu/~nottrott/tmp/DSCN4546_1989VolvoTurbo760_SeatControls_detail.JPG

and here is the bigger picture

http://lternet.lternet.edu/~nottrott/tmp/DSCN4545_1989VolvoTurbo760_SeatControls_bigPicture.JPG

The seat moved all the way forward, so that my knees were jammed
against the underpart of the dashboard, and remained stuck there -
actually a potentially quite dangerous situation. When I tried to
move the seat back again, the back/forward control didn't respond at
all, no matter how hard I pressed it, nothing. All the other controls
were, and are, still working fine.

So I squeezed out froom the seat and tried to take the thing apart,
but as you can see it is attached by some sort of "umbilical" electric
cord.

My question is, can anyone out there point me to instructions on how
to deal with this?
Any Web links, books, or descriptions of how to fix this problem?

Thanks very much for your help and advice.

Wolfgang,
Goleta, California