FWIW, I was all agog about solid state controllers and was using them anywhere there was a trace of a problem. Granted mine were thrift store finds, albeit pristine appearing. First to fail was on my GFs old Bernina. It would latch into full on. Another did the same on a 15 clone. In a pinch I use one, Chinese cheap quality shows up on these also, and I've got some of the old resistance wire controllers that I'm content with at this time.