well, I think I’ve determined the cause of death to the mux boards. same exact finding in the daylight.
both smoke units look like this one (from blue comet). the wick was completely charred and there was a lot of char stuck between both elements, basically in the form of a fault or short (if it was a piece of wire between them). Fluid everywhere with nowhere to settle.
I strongly believe that either the charred wick at some point carried a current between the elements short enough to blow up the mux, but not long enough to crack the heaters or trip the breaker....ok, maybe a long shot theory. My other, more rational, thought is that the heaters just got too hot for too long with burning wick charring against them and that caused the mux to fail before the elements went too. Either way - a combo of poor factory wicking and lack of proper use.
both heaters did survive. I cleaned off and burned off the remains and both elements work just fine. Tested the heater set independent of the engine with my little handy bench 1033 on 10-12 volts for a few seconds.
did continuity tests everywhere. all wiring was just fine, no faults, no shorts, no broken insulation.
so..... I am going to ditch the lousy factory style of wicking that failed and rewick the way I do all my others that works great. Just slice up the wick to bits and fill up the tray with a nice soft padding of wick for the fluid to drench and be held and for the heaters to smoke. I think someone called this method “Reaganizing?”
Replacement mux boards are on the way...