An internet search revealed that the likely problem was the timer. (In all modes - timed and auto dry in both regular heat and low, the timer knob would not slowly rotate to indicate the progress. The dryer would continue to apply heat and tumble clothes well beyond the point of "dry" until I opened the door to manually stop it.) AppliancePros had the part at a good price and a clear instruction video on how to open up my exact dryer - not just a similar one - and replace the timer. It really did take less than 15 minutes. I spent more time cleaning up the dusty spaces behind and around the dryer since I had to pull it away from the wall.