joe are you running the thread right off the pins on the machine ? in working with so many different machines and brands. I had nothing but tension problems.. I then went to my home made stand and cone spools. which are a good two feet above the machine and 3 feet away.. this put a belly in the thread,, which works as a buffer for the jerking motion and tension problem were gone
not saying it was a 100% cure , it sure did help