I do agree that the constant rocking of the big S&S is the issue here. Its one hell of big lump and even at high revs will be creating an extreme rocking action throughout the front of the chassis if not even further back.
I am not an engineer - but do have some experience of restoring old bikes and looking out for metal fatigue issues.
However I do hope for everyones sake - including MMC that this issue is/will now be resolved.Its easy to jump to the wrong conclusion in that the problem is not solved or will get worse.
