Jordan, that is the older style rotisserie ring. They all leak and have gaps around the bowl. I have seen some people buy wood stove gaskets to fill the gaps around the edge. Foil would probably work too as argulator said. The newer rotisserie ring"s design fits more snug (see below image). Even with the new design, there is still small air gaps.
The issue I have with the newer rotisserie ring is it can shift on you when loading heavy items like turkeys. When loading a 25 lb bird, the ring slipped downwards on the side I had loaded the spit onto. Almost dumped the bird into the bowl and lit coals. Had to pull the bird off, put on gloves and reset everything. I have gone back to the old style like you have as the tab design can not shift or slip.