N72 Output Jumping Volume/Crackling

[rthiessen]

I have done all the voltage tests, everything is measuring correctly and I was able to set the output transformer to 22.2 volts. I set it all up into my interface, everything seemed to be working perfectly for about half an hour, now it is constantly jumping from the proper output to about half that and becoming overly distorted. Also it has started to shock me, going from the preamp through the cables and into guitar strings. All of the voltages seem to be testing correctly still so I am not sure what else to do. Update, went through all of the Q voltage tests, Q4 has no output from any of its leads. Is there something in the circuit that could have fried the transistor or did I just get a faulty transistor?