My Admiral “Designer Series” dryer (don’t know the model nbr off-hand) will heat up, but the drum will not turn. I can turn it manually, but it will not turn by itself. The belt appears to be in working condition.
On most units the motor must be running for the unit to heat up.
There is a centrifugal switch on the motor with 2 contacts.
One set switches out the start winding of the motor.
The other set switches in the heating element or gas valves.
So the question becomes is the motor running?
If yes then is the belt tight around the drum.
If it sounds like the motor is running, and the drum is not turning, the belt might be off. If you get a putty knife, and slide it under the top, about three inches from the end, you will hit a clip, that will release the top. Do the same on the other side, and move the top up and back and rest it on the back wall. See if the belt is off. Tom ApplianceEducator.com