Miller Big 40G weld output at max all taps

[Cape Cod Gary]

I have a 1991 big 40G that puts out max current at all taps, my manual says that it is PCB1 but no way of checking it, P/N for PCB1 is 133759, wich is superceded by P/N 166205. Im looking for information on how to either test te PCB or if there are other issues that can cause these symptoms. I have checked my pot's, tried with a known good foot pedal, and RHC-14 with the same results. this machine also has the add on CC module.The only visibly defective component is a burned compacator on the A/I module, but i doubt that this has anything to do with power output. I will post some pics if it will help. Thanks in advance.