When I had a similar problem with my machine I finally took it in to the dealer for repair. My machine had never had tension problems which was one of the things I love about it, so when it started acting like that I was very upset. Of course, this happened right before I had a class coming up and really needed my machine. The shop called me back the next day to pick up my machine and they only had to do a thorough cleaning. Yea! I do clean my machine ever time I change the bobbin but it had gotten lint in areas that I couldn't reach, apparently. That was last summer and knock on wood, no more tension problems. Good luck to you, I know how frustrating that is.