I thought about some way to make the seal narrower but ran out of ideas. If it was stretched taller then the foot print of the base would be small and slide through. Seems logical but making something to work, is beyond my expertise. So, I called my source where I got both the rubber and new channel. I was told that they would check to see why the aftermarket rubber doesn't fit. I imagine they will try the rubber in the new channel and come up with the same conclusion I have. If they can get it slide in I want to know how they did it.
The factory rubber is discontinued which would have the smaller footprint. So you have to go with the aftermarket, but if it doesnt' fit, what are you going to do? *shrug*