How to fix a Delonghi ESF 461 ST Fan Oven?

had this oven two years - suddenly stops working. Pulled it out to find 13 amp fuse in plug blown - no effect on main switch above work surface or on the fuse board for this circuit. So replaced fuse, plugged back in, repositioned oven, bingo - worked as usual. Two days later, did it again - seems to be happening after being used and just as timer switches off (I think). Is this a problem in the switch panel or somewhere else possibly. Not an electrician, but don't want to pay £50 for the sake of a fuse - happy to if it's a real problem.