The bolt was never the problem. It was just a part that would render the gun nonfunctional and could be inexpensively returned as proof that the gun was no longer functional ad therefore nolonger a potential liability to Sears.
There were numerous receiver failures where the part of the receiver that served as the support for the primary bolt locking surface fractured and the secondary bolt locking surface was not sufficient to retain the bolt.
Note that the 583.1 through 583.12 were first generation bolt actions and the later ones were second generation.
I have copies of several failure reports in my High Standard ephemera collection.
This link is to some comments I wrote about the Model 10.
John Stimson, Jr.