The problem is with the power supply. There are two, one in the system unit, one in the expansion unit, the power supplies are identical(one sits on the bottom, the other on it’s side, but the form factor & connectors are identical). I swapped the power supplies, the SRC code followed the power supply. I see two options, find a rebuilt power supply(this is proving difficult at best)or decommission the expansion unit. Removing the cables is easy, telling the AS400 not to look for the ESU may prove more difficult, I will update when I solve the puzzle.