Symptom:
Pfaff Foot pedal sometimes runs smoothly, sporadically in speed or not at all.

Cause:
There is a small piece inside these foot controls that over time bends in half. Most likely that is the problem. Often the techs do not want to replace it and opt to sell a new foot.  I think the part is about $5.00 now. The jumping in speed is when the folded or bent piece makes a sudden contact and sends power to the machine, Be really careful when you take the control apart.  There are 2 heavy duty springs in there that have a tendency to jump out at  you.

The part is # 179 as shown in the diagram.

Gayle Farr
Nov 2006