Originally Posted by wesing
We had the same problem on our Pfaff. We think that we get lint balls or thread in the tension discs. Try loosening the tension as much as you can, then take dental floss to the discs and see if you dislodge anything. I have taken mine completely apart before, but if you do that be prepared to pay VERY CAREFUL attention to all the parts and how they fit together.
I hope you get your problem fixed. I understand how frustrating that is.
Darren
We took out the tension assembly, cleaned and replaced it when we first got it because it was not completely inserted into the machine and there was no tension. Then it worked well for a while, then started breaking thread. So we cleaned it again. Cleaned the bobbin trace and case, and it still does it.
Sigh.