That did it! So far at least... When I first got the machine, it was burning out cheap PSUs so the company's solution was to send out new beds and PSUs along with this monster MOSFET. I got an SSR while the boat was coming from China and all was well until a few days ago. The Black Widow was a heavily flawed machine but I have upgraded, rebuilt, and poured a huge amount of time and money into it - and learned a lot. It is currently a tank after this last attempt to get it right. Let's hope it works as it should - thanks repeatedly, @Phaedrux. You caught me in midair again!