For those of you fixing a pin and find yourself about 500 miles from
the nearest replacement rubber: I have found that Cyano Acrylate
(Crazy or Super) glue will repair broken rubber rings in emergency
situations. Follow the instructions and wait about 5 minutes before
returning to service. Keep the repaired area off of posts and preferably
away from ball contact areas. If it doesn't hold the first time, try again.