Hi,
I am in Australia so not much use to you, but I have a similar aged Pfaff machine and I was talking to a mechanic at the Sydney Quilt show on Friday and he said that most sewing machine repair places won't fix machines of that age but the circuit board is definitely repairable and should not need to be replaced.
I don't know if you can find an independent mechanic in your area, because those machines are pretty tough and worth keeping.
There is a great yahoo group
http://groups.yahoo.com/group/oldpfaffpforum/ that might be able to help you out.
Good luck
Glenda