I have a Thermador model RDFS30RS dual fuel range with extralow burners. The rear left extralow burner (365-11,000 BTU/HR) burner igniter sparks but the burner will not ignite. The igniter shows no damage. What parts will I need to replace to get the burner working again. We had the same problem with the left front extralow burner which was fixed with a service call/technician. Unfortunately I did not see what parts were replaced for that repair.