[Heater63]

This is not a DIY project. You can't replace the rubber yourself, but there are places to have yours rebuilt...or buy a rebuilt one. It's just a process of pouring fresh elastomeric rubber and bonding the ring in place.
see: Damperdoctor.com There is a fellow (in Oregon I believe) who does this also, I had mine rebuilt by him. Search this site as well as the web.

Also, the 230/250 are interchangeable, but not the 292..don't accidentally get a 292 balancer.

Whatever you do, DO NOT RUN THE ENGINE until you replace it! See Txfirefighters comment again.