I bring you the Filter Shaft End Play adjustment, from the IBM Selectric I And Selectric II Pictorial Reference Adjustment Manual https://archive.org/details/ibm-selectric-i-and-selectric-ii-pictorial-reference-adjustment-manual/page/2/mode/1up
It's full of these hand-drawn technical drawings that i (sort of) learnt to do in school.
Have you checked your Filter Shaft End Play today?




