When you are checking the thermostats do you take off one wire?
You didn't list the fuse and flame sensor in the parts you've checked.
Set the timer to timed regular and check continuity at T-WB, BK-BU, BK-R, T-W.
At the heat switch contacts 1-4 closed.
Here are the breakdown diagrams and Replacement parts for Maytag MGD5870TW0 29" GAS DRYER | AppliancePartsPros.com
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