Not sure that this will help you but can't hurt. Just read this on another thread here on qb. Take a piece of thread, put several knots in the thread and run that through the tension discs. Could be something stuck in there. The OP on the other thread mentioned that she did that about 5 times and some glob of gook (thread/lint) flew out of the machine and magically all was well again. As I say, can't hurt!