There is a good bit of info on Anton Largiader's site:
It may be that the damage is from the rocker blocks being too loose but I think it happens to even well spaced rockers after the miles and heat take their toll. You can sometimes get good deals on a set on ebay but most of them are being sold by breakers and are over priced. Well, maybe it's not over priced but they are expensive. I want cheap and have bought sets for less than $50. If the rest of the system is good then replacing the bearings is a good, but expensive, option. Sorry it is a proprietary bearing and only available at your friendly dealer.