The problem is that the unit is a GE Getting tech info is near im possible as GE likes to keep everything a secret.

Have you checked in the control console sometimes they like to put wiring diagrams in there.

Here is a link to a site with some GE info
http://www.applianceaid.com/ge-dryers.html

Check out #28 Sample Wiring Diagrams, then #5 Older GE, Yours may be something like this. Though it looks like heat selection on yours is push buttons and I believe the unit shown uses a rotary dial.

I do not think it will be the timer.
I would lean more towards the heat selection switch or a grounded heating coil.
To check the switch you will need a meter and the wiring diagram would be very helpful.

To check the coils
Check the heating coil.
Unplug the unit and wires to the coils.
Check it with a meter, should be around 10 to 25 ohms. Not sure on this as they are dual coils.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on high and the thermostats cannot regulate it.

Since they switch in none, one or both elements I do not think it is your thermostat since you are getting heat during air fluff (I think, from your description)

I think Item 315 is the poly/knits thermostat as it is 145 degrees and the main control is 316 as it is 135 degrees. If the above wiring diagram is close to yours but I am just guessing.

Hopefully someone else will jump is with some better info/advise.