Had bottom and top element go at different times,, thought the bottom element had gone this time but replaced it and its fine, so now got a spare, turns out after further investigation its the selector switch, as someone else has said, back two sets of electrodes in the switch burned out, and it shows when you look at the switch. The casing around the terminals has melted. Selector ordered, just got to wait for that to arrive hopefully tomorrow.
Mark, April 2013