Paul, hate to be boring, but the old man had no comment or upset or concern over perceived errors in his prior books. That concern only developed after his death. He did, however, occassionally have concerns over policy letters or bulletins that might have been issued erroneously.
One example; (forgive the semicolon) A bulletin was submitted for authorization, to be published in his name. Such submissions generally had skeletal structures of previous writings and expansion of concepts encompassing new "technology". In this submission, the old man found evidence of "squirreling". Upon investigation of the part of the new bulletin to which he objected, it was discovered that the part in question was a direct quote from an earlier bulletin, issued in Hubbard's name.
I was sent back to Flag to find the original bulletin, which had the "squirelled" section that was being quoted in the new bulletin. Find the squirrel who wrote the earlier bulletin in Hubbard's name, I was instructed, declare them and ship them out.
Unbelievably, deep in mimeo files of Flag, I found the original bulletin, containing the text which Hubbard said was the work of a squirrel.
The original bulletin was written by hand, and it was easy to recognize the flourishes of his handwriting. He'd written the bulletin a decade earlier, which contained the passages which he'd explained were the work of a rampant sp squirrel.
When I returned he asked if the squirrel had been declared and kicked out.
I studied his face, the thought fleetingly passing through my mind that maybe I should tell him it was he himself who'd written the passages which he now so venomously condemned.
But I didn't. I assured him the matter had been taken care of.
I have only rumors from reliable sources on his death, but nothing which I can repeat with any certainty.