John,
The manual answered my main question: what do those levers do? (two are for fresh air, two are for heat--now I can finally turn off the heat in 90 degree weather!)
Bob,
Yeah the one electrode was pretty well rusted away but maybe if I clean the rust off the bit that's left will work. It did seem that there was enough there that it ought to make contact but probably the rust was interfering. How best to clear rust off an electrode?
Thanks again for the help guys,
Sky