Remove the two burners and clean tubes with a rod with a cloth on it to remove and thing in the tubes. Place the burners for a couple of hours in a sink of Apple Cider Vinegar. Make sure it's Apple Cider Vinegar, I've used this to clean gas burners for years!!! This will remove any build up in or Outside the burner. Let burners air dry. Rome the orifices from the effect burn controls and wipe out the inside were the orifice screws into the switch with a Q-tip. Check the orifice holes to ensure they are clean(small needle)do not enlarge the hole, the orifices can also be soaked to the vinegar. Reassembly and try.