All of the rings on our range seem to be only partially working. We have to light them with matches as the ignition is clicking but not lighting the gas. Does anyone know how to clean them? We do clean the top every day but I reckon it's a build up of spills and things boiling over causing the problem. mil seems to think that a soak in hot soapy water and a scrub with wire wool should do the trick. Any other tips? Thanks!