Selgas
If you gas cooker is connected to the gas supply by a flexible hose that plugs into a “bayonet type” fitting ( which in itself is an isolating valve ) it is possible that when the cooker is pushed back into place the hose may be under some pressure forcing the coupling in the bayonet to not connect straight into it and being on a very slight angle it is possible for a very faint leak to develop. In saying this if this were the case then the leak would be present continually well for as long as the cooker was pushing back on the hose.
To test for any possible leaks your gasfitter should apply a manometer gauge at the gas meter test point, then shut the gas meter down and check after 10 minutes or so if the pressure on the gauge has dropped – if it has then there is a definite leak somewhere. A soap or detergent squirt over joints will not always indicate a very small leak and it even at times temporally seals it off until the detergent disapates. Another oprion may simply be that one of the gas valves on the cooker is allowing a very small amount of gas to pass through to one of the burners and that is where the smell is coming from – this would be my first thought given the smell is intermittent and difficult to locate.
Hope all of this helps.
