This leads to the gas hob. Slight eggy smell from it accumating in cutlery draws. Registers one additional cube on my H61 gas tester. Uses 0.01 or 0.02 kwh gas overnight when no appliances are on. Years ago my plumber put a new isolation valve in the cellar because she couldn't find this one when fitting the new hob. Question is can I stop the leak by tightening the nut or should I just leave it alone. Could get the plumber back I know but trying to be frugal.

