You didn't say which Pfaff you have. I had trouble with my 1471 about 9 years ago that I couldn't raise the presser foot to unjam the machine. Finally got it up, but then it jammed again. Turns out it was a crank roller or IDT roller. At the time, I was able to find the part and replaced it.
Janey - Neat people never make the exciting discoveries I do.