Last week I purchased a new Whirlpool Range with smoothtop and convection baking. In my User's Manual, it says NOT to place foil in the bottom of the oven (I too have the hidden bake element), instead place a piece of foil on a rack under my baking dish. I really don't know what you would do to take it up.........maybe lay a wet cloth over it for a while and see if it will loosen it! If that does not work, call the manufacturer of your range and see if they have any suggestions.

On the appliace forum one member suggested that aluminum would disintigrate at high temps so run the self cleaning cycle. Well, it did not work. I guess I will contact the manufacturer as has been suggested before I try anything else.
Thanks.