I have an ESTATE by Whirlpool Gas Clothes Dryer. It started kicking off in the middle of the cycle because it was overheating. I had a dryer guy come out and he changed the thermostat, the hi and low end regulators, traced all the wires back to the source and we are still having issues. He did notice that the gas burner is not shutting off. Any ideas? I don't want to be charged for hours of not finding the problem!!