@ Augustus
I used the original triac (T25QC6F), 600V, 25A, TO220
@ Alfons
Good question. I am on a business trip, when I am back I will take a look at the signal
I would expect the following
1 Ground
2 Heater supply
3,4 Temp Sensor feedback
5 Signal of movement (ON, OFF)
May be time to closer inspection of this PCB?