I would disagree that the dropping resistor should/would/does glow red hot under normal circumstances. For one thing the resistance element or coil is potted in a high temperature ceramic coating and would emit any color. If it was glowing then the ceramic potting compound is probably blistered off of the coil. So if it is literally “glowing red hot” then the coating is probably missing which is exposing the bare resistance wire to the atmosphere and allowing it to become oxidized and eventually burn out.
So I would say that for some reason the circuit is pulling more current than it was designed for and that the over heating has already damaged the wire wound resistor coil on the back of the switch.
Denny Graham
Sandwich, IL


Denny G
Sandwich, IL