This Whirlpool dryer works fine on low heat and fluff temperature settings, but on high heat setting there is no heat though unit spins normally.

I found the circuit diagram, attached. I can make some sense out of it.

I guess I also need to check the switch contact AH to AH1 because it looks like the motor will run even if the entire timer & heater were shot.

If good, I would then need to test HT1 and HT3 but dont know what they are or where they are likely to be (control panel or down by the heater somewhere).

N.C. would mean normally closed, though I am not sure what I would be looking for here, if all the above test fine.

Any help is welcomed. Thanks! In past years have fixed/replaced the heater (twice), door switch, and motor, but that seems like ages ago and may have been. The unit is 20 years plus.