i have seen that before - we did not come to the same conclusion you have although i see how you did

the China bolts are garbage gold colored cap screws - on one motor what we found was the bolts were streaching and by doing so // becoming loose enough to cause a chatter, that looseness and chatter caused a metal fatigue But another issue is also at play, and that being valve spring pressure, my guess as i have no idea about what your running - if its way to high maybe 180 lbs closed making it 345 open or more and also i do not know as you said you had Jims lifters and the hydro solids are great BUT they never told any one they pump out at high RPMS - we found that they move ,060 at the very least up, so valve spring coil bind becomes a very big issue in this

you will need to look at he top of the valve seal and the winds on the spring to see if in fact they were bottoming out or not

you need to re do the installed height of your spring and retainers - the travel of the valve - and the coil bind of the spring you have < that is the one we found to the issue

we found the one motor had bottomed the valve spring and caused the broken shaftstay --

But again i do not know what ypou have but i can walk you through it if you need to know how and what is done

 

That is terrible! Did they fix it under warranty or are they in denial?