[Yo-Yo]

The ‘ultimate evidence’ is the presence of different versions of the same letter, like capital “A” within text supposedly written all on the same typewriter back in 1961.

Have you ever actually seen a document typed on a manual typewriter using a fabric ribbon? I went through college typing my papers on one, before there were such things as word processors. (Oh, they were beginning to appear in basic form on computers like Apple IIs or TRS-80s, but most Professors wouldn't accept a paper printed using a dot matrix printer.)

Combining a fabric ribbon with computerized scanning, I can believe all of those letters match.

[danamco]

Then you had difference in the clarity of letters when the ribbons came to the end and would not shift direction automatically. The writings looked like when a printer cartridge is going down in ink!!!