.012 does seem excessive if due “wear” and probably not prudent to reuse even with packing, although from the few I have seen seems the nut often loose and the spacer worn which would account for.
The inner track each of the 38MJT25 pair looks rather worn and scored so I expect that is where the end float is caused.
I did tighten the nut up a little ( about 3 degrees of turn to check if spacer between thrust pair and roller had "shrunk" a bit but no difference.
I am a retired electronics professional and my mechanical engineering knowledge has only been gained over the years from playing with old cars and reading up on various aspects and some from experience when working on our ships on the mechanical bits involved with the electronics e.g. radar scanners and various sizes electric motors etc.
So my mechanical engineering knowledge is quite well down the information scale!
I have a medium size lathe but lack the skill/knowledge to do anything really meaningful/skilful with it and certainly not precision work!!