It's odd that this should just come up, I just had my Defroster from IM break in the same manner (rusting under the magnet). Suggestions for fixing this would be greatly appreciated here as well.
On another note, I've had to call IM twice in the last couple months, once for the Defroster, and a second time because the clamp that holds the light onto the tank broke. Their customer service is great, when you can get a hold of them.
Jordan