A professional longarm machine quilter for hire and some of the work I've done.
Having trouble locating the problem? You say you have tightened the tension…. loosened the tension….. re threaded more times that you can count….. tightened the top on the rollers….. loosened the top rollers…. cleaned and oiled the machine…. re timed the machine until you are cross eyed…. changed threads….. asked your internet friends for suggestions…. called the repairman in desperation….. and still having problems of breaking thread? AAAARRRRR!!!!
I can’t tell you about other machines but I can tell you that the Gammill machines are extremely sensitive to the very tinyest little things. It can take hours to track down the source of a problem because it might be so small you need a magnifying glass to spot it. Before you decide to take a hatchet to the machine so you can toss it out the window…. here’s one more thing to try when you are having lots of breaking thread or intermittent tension issues.
Take apart your tension assembly and check the felt disk. Is it dirty? This dirt puts drag on the tension disks which causes tension problems. Check the disk for lint and dirt inside the center hole. See how dirty mine was? Also, inside the center hole of the disk is a tiny, tiny little groove. It’s where the two sides of the disk come together. Sometimes there is lint inside this that you can only get out by using the pointy end of a needle.