[Speedslug]

You mentioned that you "dug the kiln out", did you make sure that nothing made a home inside the controler?

Small critters are really fond of finding small spots to live in and if they managed to cross a few of the electronic parts on the circuit board with webbing or their own bodies it can radically change they way the controller functions and won't always trip a circuit breaker or blow a fuse.

I know there are red ants that simply love the area around live switches and I have had brown ants attracted to some of the soldering flux left on circuit boards when they leave the factory.

My other thought is to wonder what kind of glass rod you are using in your 'sag test'.
Soft glass in white will melt if you just look at hard for a few minutes while most of the transparent blues I play with need some serious persuasion in the torch flame to get it to flow and even then it will stiffen up if you take your eye off it for a second.

Good luck with finding a fix.

Oh and look for screw contacts getting oxidized after a long time in storage.
I take the screws out and rub them with a pencil eraser to clean off the invisible oxidation layer on the leads and the screw pads if I'm chasing down funky symptoms while troubleshooting electronic systems.