I took the oven out, marked the 4 wires and replaced with new element.
I have got a multimeter but the manual only deals with the user and doesn't show engineer's details. i.e voltage readings. The wiring on the element from right to left at the rear is yellow-blue-black and the 4th connection is linked to the 3rd. The outer connections are to the outer perimeter and the inner 2 are to the main centre element.
Yes I replaced the top element, the bottom one is working OK. The top element seems to work OK on the grill setting.