Interesting that I dug mine out of storage today and found out that the polyurethane resin I used to re-restore it last October had sagged pretty bad (see pic) and needs to be redone AGAIN!

They say the third time is the charm.

If you have one that the rubber has gone bad on, they can be repaired. Shoot me a PM if you'd like some info on doing that. Cheaper than buying a new one (assuming you can get the right stuff to revulcanize it.)