Jack Glendening wrote:

at this point is that there is a nut on that bolt at the brake case
(as a spacer?) and the shearing occurred just outside that nut.

I don't have a tost wheel in front of me right now, but I'm certain that
there is *no* nut on that bolt as a *spacer* (maybe a washer, I can't
remember). There is a nut on that bolt outside the "receptical" to
secure that bolt. So if your mechanic installed that bolt inside that
"receptical" (e.g. as a spacer), it's pretty clear that the bolt would
slip out, the plate would rotate and that bolt would eventually be
sheared off.

Just a guess based on your description, I may have understood you
completely wrong.