I have a similar problem now. I am assuming it is the heating element as I have removed the internal back panel from the oven and found a circular heating element that won't heat up so this sounds like your problem.
I have found a webite with new parts for Belling and many other makes called espares. I am now trying to find out how to remove the old element from cooker but Belling seems to have riveted it in. I will try to let you know if I make any progress.
Martii
April 2009