I can start the dryer cold and it operates correctly. When the dryer gets up to temp (max limit thermal switch tested ok) the burner shuts off. After the thermal switch cools, the ignitor comes on and I can hear a sound like bad contacts or a shorting of wires. I then hear the coils engage but no flame. The ignitor goes out and the cycle will repeat until I let the dryer cool to room temp.

I have tested the 2 prong max limit. It's ok
Tested 4 prong limit. ok
Tested fuse. ok

What is the need for two coils on the gas valve? Is one for "priming"? Do the coils perform different when hot? Do they fire together?

Thanks in advance!