To finish the story----
The green stuff did not come off with vinegar (6% acidic) perhaps because I could not soak the electrodes in place, don't know. Had to scrape them and got most of it off. Everything is back to working for now.
The two electrodes are there forever, rusted on to the hanging bracket also rusted on there, with their own little brackets, so even if the screws were drilled out, they will stay stuck. The sensor electrode is corroded, so I will have to figure out how to replace that someday, but not soon I hope.
EDIT just got a Norcold 641.3 off a guy, so that will be the new fridge. I am tired of keeping this OEM one going.
