Great work!! I only remember a tiny bit from the early 80s about transistors but as I recall, the base ("P" of a NPN) is the switch that allows voltage to flow from the N to the other N when the base has a positive applied and thus, the P is energized and opens the gate or turns on the switch as they say. So my question is whether or not frequency plays a role in the MOSFET? In other words, I suppose it can only swith so fast and if so, how do you see that marked on the transistor when you search for one to purchase?

OR... are you saying that the freq is not a factor and you are merely concentrating on the increased power?

With all these going bad, I'm wondering if the MOSFET can't handle the load once the parts get old and/or is heat the reason for them going bad?

By the way, can bearings be replaced in these and if so, do you know of a source?

I truly look forward to the update once you figure this out....