Rosieres Paul Bocuse DB4040 oven fault

Right hand (fan) oven overheated when baking – enough to burn oven glove and blacken cake tin and now doesn’t get to temperature yet gets hot both top and bottom. Right hand (non fan) oven functioning as it should.

Is this an element dying with a last super nova burst or Do I need replacement thermostat? If so should I also fit a thermal cutout as a belt and braces approach or not necessary? Do I access behind thermostat panel by lifting heavy cast top if this is the problem and how easy is access?
Happy to diagnose further if given hints.

Many thanks for your help in advance – loyal customer – Shoebox