I second the advice. I have done this procedure myself and had no problems whatsoever. While not proof positive, most likely it is a misconnected pin. But if I had to hazard a guess, I would bet you did not isolate pin 1 well enough as this is the power transformer pin section. You have to really cut into the board to ensure you got the entire trace. Solder on pin 12 bridging the circuit could be a problem too. I doubt it has to do with sense mod in step 3, but you never know.