My friend took care of transporting the unit a few days later, during which time I was working a short-term job. He had to lay it on it's side in an SUV. When we got it to the shop, and finally got it installed, Stick mode worked, but TIG didn't. We tested out the foot pedal, but it passed. There was no indication (HLP) message displayed.
After taking the pedal in to a local Miller rep and getting it tested again, I was sure the problem was going to be the control board. I poured through every connection, and it still looked like the problem was the remote control pedal. Finally, I wiggled the connector-plug junction on the inside of the unit, trying to unplug it. The PCB soldered to the connector came completely off! Looking at it, there appeared to be cold solder joints between the pin sockets and the solder vias.
I repaired the connector by heating the connector components to the pads again. After double-checking continuity with all pins, I reinstalled the connector. The welder worked, good as new - TIG and all!
Hope this helps someone. My hick.org email address is rixon. Or rixoff on gmail.