I have a problem with an AEG Competence oven - the main oven heats up OK but after a few minutes it trips the power. My cousin is an electrician and he checked the circuits and things and suggested the thermostat might be the problem. I replaced this today and still have exactly the same problem. The heating element was replaced around a year ago - I have taken it out and it looks fine, no sign of cracks or warping or anything. Is this likely to still be the problem? Any other suggestions would be appreciated!