[PaulR]

I wouldn't think that the reflective panel would cause problems unless it was touching something live. You would probably get a flash and a bang in those circumstances. The outside of the cooker may get hotter than previously, though.

Your problems with it tripping the electrics is probably due to damp in the elements. It doesn't take much and it has happened to me with elements stored at ordinary room temperature. If you haven't already thrown them away I would keep any of the old elements that look in reasonable condition as they are a diminishing resource.

Getting it warm using a hair drier or similar might help but it needs to get pretty hot to drive out the last vestiges of moisture.

Would you feel confident to disconnect the earth from the cooker at the wall and get it hot in that condition? Obviously you would need to switch off the mains to the house at the main switch before starting. Having disconnected the earth you could keep everyone away, leave the cooker's wall switch off, turn on the grill and oven then throw the wall switch. Let it get hot without touching it then turn it off using the wall switch and reconnect the earth. Obviously you would need to take great care and not let anyone touch the unit whilst it was switched on. If you are at all unsure about how to do this then DONT!