Hi Steve,

Your thoughts are along the same lines as mine. But you took it a step further by inquiring about the vibration it was expected to perform under, and whether hard was better in that application.

I'm sure there's a heck of a back story to this fractured bolt, but I'm not yet privy to the details.

And I wonder, if I checked some of my junk bolts with a file, if I could tell the difference or get good at scratch testing, or is this something that can be done cheaply and easily at one's friendly automotive machine shop.

Thanks for your careful response. Will update if I hear any more on this.

--
Art Benstein near Baltimore

What engineers say and what they mean by it:
"Modifications are underway to correct certain minor difficulties"
We threw the whole thing out and are starting from scratch.