The left side (as you look at the front) rings are not working and the light on the fan assisted oven doesn't fully go out. If I try to start either of the left hand rings or the grille, the clock goes out, so then the ovens don't work. I replaced the outer element of the non-fan oven but it has gone through all the workload of Christmas with no problem. I suspect the problem is the left front ring (leftmost switch) as it the problem arose when it was switched on. How can I tell?

John Piper, January 2012