Yup Joe and Candace are right - clean it up some more - the zig zag linkage. I have a Pfaff too months to free up. Something in the linkage was stuck. I cleaned everything up as best as I could get it. It still wanted to not return a zig zag. Finally I used Tri-flow and set it under the bench. Every once in a while I used more T-F and turned the machine on a different side so the T-F would flow into where ever it was that wasn't moving. I just kept turning it over. I would turn the knob once in a while to see what it was doing - hit it with some T-F and one day it worked. I don't really know what exactly was stuck - but it was varnished up pretty good like yours. It can have some stuck inside somewhere you can't see it. The T-F works quickly most of the time, in that case it was very slow. Now the machine has a different problem...