Checked out Convection Oven. when oven is turned on, pilot lights but when thermostat is turned on, valves click but burners don''t light. found that safety switch thermocouple is not cherry red and not sending voltage to burner valve. if power turned on and wait til thermocouple is red burners light when thermostat is turned on. cleaned pilot. was a little dirty. explained to customer that safety switch can''t be replaced due to fact that is mercury switch. also told customer to power on oven in morning, set thermostat to off, and wait a few minutes for thermocouple to heat. now powered on, pilot lights, wait til thermocouple is cherry red. turn thermostat to 350 degrees. burners light, but valve keeps clicking. found if safety switch is moved by hand, clicking stops. made a bracket to prop up safety switch. let unit cool down. powered on. let thermocouple heat. turned on burners. burners lit. no clicking sound. unit heated to set temp of 350 degrees. cycled. no clicking from valves.