I started by pulling up Youtube videos about Whirlpool dryers that would not heat. The videos showed simple steps to test the electrical resistance and continuity of the heating element and related thermostats. The thermostats checked out fine in both tests, but the heating element failed on both. I ordered the heating element, as well as the two thermostats (might as well spend the added $29 to replace them now, while it's easy). Parts replaced, and the dryer works just fine. Thanks Youtube and AppliancePartsPros- I figure you saved me about $250 in labor.