Nope. it was the slide motor. It shorted out inside and drew enough juice to cook the switch. The new switch appeared to fix it with a quick test, but as soon as we tried to do a full extension, the breaker kept resetting itself. The switch got real hot again, and that's when I knew.
We stopped at a great RV dealership in Cranbrook, BC, Canada, called Runners RV. Super people there. Just to confirm my suspicions, they threw an ammeter on the line, lo and behold, the 30 amp rated motor was pulling 78 amps. I cannot overstate how super and helpful these people were. if you're in the area, and are in need of a good crew to help you out - Runners RV in Cranbrook, BC.
They didn't have one in stock, but I was able to order one brought in to our local dealer in Alberta, and it was here when we got back from holidays. I put it in, and it appears that it is happy again.
Thanks to everybody for their feedback, and other posts, that helped. And huge thanks to the folks in Cranbrook.