Thank you all!
I will order part # 33082 to see if that will fix it. One question though - if the sail switch is the problem, why do you suppose that resetting the on/off breaker switch by the board RELIABLY fixes the problem, for a week or two, until it happens again? This has happened maybe 8-10 times in the last 3 months, and every time, resetting the on/off switch at the unit causes the furnace to immediately light, first try.
Answering the other questions:
1) I am on shore power - plugged in to 50 amps.
2) Does it light and then go out (yes/no) or does it not even try to light.
It does not even try to light until I reset the on/off breaker, and then it lights immediately
3) Do you hear the CLICK of the gas valve, the snap of the ignition system or not
No I do not