You need to change the thermal fuse which is screwed to the main body of the oven.
Turn of the power source or knock down the circuit breaker on your fuse board first.
Remove the back panel to right hand side, the thermal fuse is on the right hand side of the body,it's round size of 5p easily removed.
You need to order the new one on line, you need to match it up.
Then reinstall.
Chas GANNON
August 2013