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Replacement parts for MAYTAG MDE9206AYW DRYER- ELE | AppliancePartsPros.com

Here is the service manual
Download 1998 Maytag.pdf

As you can see from the wiring diagram (Page 9-1) the unit does not have a moisture/dryness sensor.

In timed dry the timer motor gets power directly through timer contacts 1 and 2.
In permanent press timer contacts 2 are open so it gets power through the temperature selector switch in air fluff or the cycling thermostat RD/OR contacts and the temperature selector switch. RD/OR are normally open so when the thermostat shuts the heater off they close, advancing the timer.

Set the unit to air permanent press if the timer does not advance then the selector switch may be toast.

To check the cycling thermostat you will have to remove it from the unit and heat it up to see if RD/OR close. This can be done on an electric stove element or use a soldering gun to heat up the face. Be sure to make a note as to where the wires attach also be careful to not burn yourself.
When it hits it's trip temperature RD/PU opens and RD/OR closes.
You could just take a gamble that the cycling thermostat is toast and replace it as it is the most likely cause.

There is a chance that the cycling thermostat is not opening due to low temperature generation and therefore the timer does not advance in auto modes.
But you should have noticed longer dry times.
If this is the case.
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
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 give low heat all the time.