Well Folks, it just goes to show that some days there's nothing to do but throw you hands in the air and smile.
With the good advice from this forum I mustered the courage to pull and tug till I managed to get to the plates off and get to the "guts". Took the furnace out, blew it out with compressed air, sanded the electrode and cleaned some more. Slid her back in and ....... nothing!
Droped it off at the dealer with my almost expert opinion that it had to be the circuit board and left! They called the next day, (the guy on the phone was smiling, I know he was!!) to tell me there was nothing wrong! They took the furnace out CLEANED IT, slid her back in and, wouldn't you know it, it's working fine! Nothing an hour's labor charge couldn't fix anyway! Just to be sure we took it for a weekend run (nights here are now VERY close to freezing) and it was "A" OK! (or is the OK, eh)
Rest assured, I'm not complaining! I wish all our RV problems were so easily cured!
Thanks for the help and advice!