Getting ready for an Alan Gunn R914rsr leather kit last night and found a solution to the deteriorating rubber. The top was separated and the rubber was in bad shape. I drilled some holes in the separated section and blew some water in the holes. Then I forced original Gorilla glue in the holes. Then I used a small brush typically used for flux to cover all the rubber. I used the brush to keep the sections that were ok from expanding and let it expand where chunks of rubber were missing. Sanded it this morning with 80 grit. I didn’t need to get it perfect because I think the felt and leather will cover but I feel like with more work I could have almost made it perfect.