If the slot that is cut is too deep. There are two options:
1. Ignore it. It fits just the same
2. Use a larger bearing. It won't cut the slot as deep.
Lookup woodworking in the phone book. Take a piece of t-molding with you. They will sell you the cutter, the arbor, and the bearing. I recall the price as reasonable, but couldn't remember what the total was. Definately a lot less than the $31 that t-molding.com wants for just the cutter without the arbor and bearing.