I'm running the Chop-Rite #10 that my parents bought in the 1950s. They had only the original 3/16 "hamburger" plate and they never sharpened the blade or polished the plate. When I got it, I could see how the blade-plate contact was not even because the finish on the plate showed light and dark areas, mainly dark in the center where the plate had worn after half a century of use.
I used a diamond sharpening "stone" and it was easy to sharpen the blade as shown in those videos. The plate took much longer and the finish could still be better, but the results were clear. I got much less meat being mashed without passing through the plate.
However I suspect the auger is worn from its original specs. I can't be certain without a caliper and knowing the proper spec but it looks like the edges come to a flat end, like shaving the top off of a ridge. There's no way to fix that by grinding off metal; the only fix I can think of is replacement with the hope that the new auger will mate well with the bore of the grinder.
Edited to add, I also suspect that the shaft of the auger, which passes through the central hole on the plate, is worn and allowing more wobble which would throw off the mating accuracy of the blade-plate contact.
FWIW the Kitchen-Aid grinder I got from my parents was much newer but in much worse shape. The plate surface was visibly uneven.
