After checking everything multiple times I got a price of $245 for a new control box from my "local" Quadrafire dealer.
Rather than waste precious time (minimum of an hour) and gas driving I just had him order the box.
I know I'm taking a chance by not trying to test my control box in his stove, but I want my stove working again ASAP.
I see no reason why something else might be the problem.
I'll update this thread when I've got new control box plugged in and hope to post picture of working Castile insert.
Thanks to all for the help. I do enjoy trouble-shooting my own stuff. I learn a lot in the process.
Before this issue I had no idea what a snap-disk was.