Make sure you have unplugged the electrical supply before you start anything
If you look through the holes at the back you will see two torque screws that hold the back bearing. Undo these fully, they won’t drop as they are captive. Make sure you have all the other screws out from the rim at the back that you have already talked about in your question there are about six all stainless steel torque head. REMEMBER make sure all electricity is turned off. Once you have the back out you have access to the heating element, take the three cross head screws out and pull the whole box out gently, there are two sensors so you will have to unplug the jack and get the plastic plug free from its housing. You can check the continuity of the element, if that’s OK it will most likely be one of the two sensors.
Tom
February 2006