I have done a little detective work and can't find any evidence that such notebooks exist, or ever existed. I did a general Google search as well as a search of Google Books and all that I found was the original reference to keeping notes contained in Five Lessons and a handful of references by others to that source. No mention of actual notebooks was found anywhere, nor was there any other instance where Hogan or those close to him talked about him keeping notes.
The closest thing I could find was from James Dodson's Ben Hogan An American Life. Dodson wrote his Hogan biography with what was represented to him as full access to Hogan's personal correspondence and other items, but found that "only some of [this material] turned out to be helpful; Hogan, for example, kept minutely detailed expense and travel diaries and derived great pleasure from dispatching formal letters and puckish notes to his friends but rarely if ever committed his deeper feelings to paper".