Timer won't advance. Already replaced timer. Post from 2012 indicates could be "dryness control board" AP6007980 which is no longer available!

Dryer Repair
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Brand: Maytag Neptune
Model Number: MDE4000AYW
Main Symptom: Timer won’t advance
What happens & when: Timer won’t advance on both automatic and time only settings. Runs until stopped manually. Tumbles and heats normally. Already replaced timer. Post from 2012 indicates it could be the “dryness control board” AP6007980 which is no longer available! That dryness light still lights up and changes from 2 lights to 1 but not to 0. Could it still be bad? Is there an aftermarket sensor that would work? What else to try?
Chat suggested checking the new timer to ensure that it’s not bad out of the box. I’m not sure how to do that. I have a multimeter and the schematic that came with the machine. But it’s been a LONG time since I’ve traced and tested an electrical circuit. I could really use some guidance on what to test and how. I also have the wiring diagram that was on a previous post but it’s not clear enough to tell what the wire colors are.

Error Code (if any): none
Parts or tests already tried: replaced timer, cleaned moisture sensor with rubbing alcohol
Photos / video link:

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Voltage to the timer motor can be tested using the gray wire and the brown wire on the timer. If there is not 120 Volts AC when testing these two wires, the dry control board has failed and is preventing the timer motor from having a complete circuit. Unfortunately, it does look like it has been discontinued like you said, and from what I see in this link. WP33002389 Dryness Display | Genuine Whirlpool OEM In Stock