I have a feeling I raised this a few years back and now the problem has returned. When Madam is cooking, she lights the gas ring and finds unless she holds the knob in for a long time and then even after releasing it, the burner goes out. This can get quite fractious and annoying to her. I think it was suggested that a thermo couple might be the culprit. On getting our mobule local chap in who said it wasn't the thingy, he pus some ali foil inside the knob and said that will hold the gas button on. It seemed to work fine and that was 2 yrs back, so maybe I need to stick some more foil in.