An appliance technician came to look at it. He said it was either the control board, the thermal cutoffs, or the drum belt switch. He said he could take the machine apart, but it would be hundreds of dollars for his labor and hundreds more for a part. He recommended replacing the dryer, which is 8 yrs old. I found a video online on how to tear down and troubleshoot and found the problems myself. Some material had made it through the lint trap/filter and jammed the blower fan. With the fan not turning efficiently, heat built up causing the thermal fuse and thermistor to fail. Replaced those parts, cleaned out the fan, and I am back in business—for much less than the cost of a new dryer!