[Dentlord]

One thing I noticed mounting the Fatboy is that the square which contacts the core is a little more raised than the slims.

The first time I mounted there was a gap all the way around. Just use a thicker layer of eraser around the core, or do what I did and make a "gasket" of armaflex tape around the core on top of the eraser where the Tek will be, so it seals to the Tek insulation.