The best next step to take would be going through the drive with TK’s “Universal Drive Tester” You remove the Amp Traps, power up the controller and supply the drive with 120vac through a 100 watt light bulb. Then there is a box that plugs in between the current reg & firing card and the regen board and firing cad that lets you manually fire each IGBT. It would be well worth the effort if you could get a hold of one.