Originally Posted by virtualbernie
Originally Posted by katyquilter
I'm about to try a plastic bobbin in my 99K which I recently purchased at a thrift store. It came with one metal bobbin and I bought the metal 66 bobbins which should work. they fit but do not work - the machine refuses to sew, it's as if the bobbin is just a hair too tight. So someone suggested plastic. I'm going to have to get some to try soon unless someone has a better suggestion.
If the plastic doesn't work, try adjusting the tension screw on the bobbin case. WARNING: YOU ONLY HAVE TO TURN THE SCREW JUST A HAIR--TOO MUCH CAN CAUSE PROBLEMS!
I have had to do that with my older machines, never with the new one, I suppose it's wear n tear, and I agree with your warning, just a tiny smidgen and then test the running of the thread. This video is a super to show you how:
http://www.youtube.com/watch?v=TaH9yB7XUBk