Need Help on a PCB for a Lincoln Power Mig 180C

Hey dude any luck on this? Took a look at the schematics, have some ideas on troubleshooting it if you can probe the IC's. I have a Mig-PAK 180 as well, I was thinking of hot rodding mine so this is an interesting thread. WRT the schematic on page 110 of the service manual: Looks like the SCR triggerring is enabled through an optocoupler OC11, which is basically a comparataror (i.e. outputs on/off. not a level) comparing the sensed output voltage via X7 pins 1/2/3 and the set voltage. X7 pin 8 will basically output vout minus vset, and is compared against a threshold in X7 pins 5/6/7. So you could probe the X7 pin 8 to see if the output follows the voltage set knob. See if X7 pin 7 has any activity - should be pulses which you could measure if you get a small cap and resistor and RC filter it. And what about open circuit - on mine, you can measure different open circuit voltages when you adjust the voltage knob - just turn down the WFS and lift the feed roller tensioner so the wire doesn;t run when you hit the trigger. It could be a bad xfrmer that has a short or high impedance that runs OK under no-load but can't drive any real current if OCV looks good but voltage is low when welding. Could be a bad optocouper, coud be lots of things but if you can probe some of the points you might have a better chance of tracing it back.