[FatBoy]

Hi Paul,
It is a relatively common problem. I had a 427 S/O with all Crane valve gear and over a period of 2-3 years, I broke 4 rocker shafts. I assume it has broken across the end post. The problem is that the end rocker is unsupported and with a high-performance valve train, the loads are very high.
There are a number of products that include modified end posts that fix the problem. Some of the higher end products also include full roller setups and look very "sexy".
Contrary to what trularin has said, I don't think you have a problem elsewhere and you don't need to dismantle your engine.
Sleep easy :-)
Regards
Paul