My guess would be a coin counting machine. I see a lot of that type of machine damage on Kennedy's nose or the Eagle's beak (halves) and never did before the prominence of the coin counters. I think what happens is a coin gets "stuck" against a roller of some type and it can shear off an area.
I think in this case it is just worn. However, usually graese filled dies will show no lettering at all. A weak strike, you would see the intended letters, just less bold.