According to the symptom analysis, fault location may be in the barbecue grill microwave oven or heater control circuit. After opening the lid to check the measured power grill heater. Grill heater installed in the furnace top, the two series of 500W quartz heating tubes arranged in parallel installed. Open iron grill heater cover, two quartz heating tubes were measured with an open damaged. Put a new 500W quartz heating tubes, installed shell test machine, everything is normal.kGQservice manual download site