I got the replacement mosfet, and some precision 10 ohm resistors. I also got some high speed high power schotty diodes to dump the big HV spike into the capacitor bank instead of letting the voltage stress the mosfets. This is possibily an overkill, but I will be making millions of welds with this thing, and don't mind spending a few bucks getting things as solid as I can.
This buss will connect with a copper buss bar to the capacitor positive buss. Any voltage greater than the capacitor bank voltage will conduct through the diode and buss bar right back to the capacitor.
That's the plan, will soon see if the plan works.