John,
The rear transmission mount that I received had no rubber left at all, so there was nothing for me to clean out. I have read that others have used a torch to remove the old rubber, but I have no experience with that.
The top and bottom pieces are attached together with very impressive rivets which pass through oversized holes in the middle plate, so they move very easily once the rubber is gone.
By using the clay-like material, I was able to position the parts so that the rivets were centered in the holes through the middle plate and the Enduro Flex was able to flow through those spaces to fill the voids.
