Gas dryer starts fine ignitor glows and gas lights with nice blue flame after a few minuets the flame goes out but dryer still tumbles on. Tried both regular automatic and timed heat with same results. Taken apart and cleaned all vent, fan, drum. I note two thermostats one called high limit located at top of drum in back of the unit and the other labeled Control Thermostat in the front. Would either of these be the cause of cutting off the flame?