Originally Posted by
Surfergirl
Sometimes you have to remove those two tiny screws and remove the tension spring to clean behind it. I've had to do this several times. Sometimes rust forms or thread gets caught there...the tiniest little thing can make it impossible to adjust the tension on the bobbin case.
I do that usually but if you have never done it is can be a scary thing to do. You would want a copy of a service manual and a best friend to help. Keep things in order and don't lose any little parts.