I was under the impression those were for use in the bobbin case of a dsm when free motion quilting. My longarm bobbin case has a flat spring in the case under the bobbin. Those do wear out from time to time, and need replaced. In the past when I had tension issues I couldn't seem to fix, it was because something, usually a spring, had worn out and needed replaced. I don't have a HQ, though; I have a Gammill, but I would think the same should apply to any longarm. The beauty of industrial machines is that when parts wear out they can be replaced, unlike dsm's.