The dryer I worked on last night turned out to have had a bed heater contactor that had welded closed across the contacts. This caused the heaters to remain in an energized state indefinitely. ..which ultimately led to the meltdown condition.
Welded contacts are a typical problem for contactors that resistive loads with dry contacts.
Additionally, the dryer was designed without fuse protection in the heater circuit.
The manufacturer designed this particular dryer model to rely on only control monitoring parameters to avoid this problem (setting over-temperature limits, etc.) Which we will ensure are set correctly once repairs are complete.
As it stands, the majority of damage was done to the hoses, dessicant, and some insulation.
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