I don't see the grinder marks.
I do see horizontal scratches across the upper numbers.
Could have been made by someone rubbing with their fingers. But they also look like file marks. Occam's razor says they are finger rub marks.
Here's the thing, though. Those numbers were not stamped in by a machine.
Save both of those pictures to your computer. Bring them up on screen. Spin them so they are oriented correctly.
Now use a piece of paper as a straight edge. Put it along the bottom of the numbers in the second, (factory) pic. See how crisp and clean the bottom is? Beginning to end they are all perfectly level, and stand perfectly vertical from that line. The only variance is obviously intentional. (Extra space after the "T", and a little less extra space after the "U2")
Now do the same to the first pic. Those letters and characters are all over the place. The "F" sits on top of the leg of the "L". Spacing is not consistent anywhere. What spacing is supposed to be there, isn't. And there is spacing where it shouldn't be.
Best job they did was with the vertical placing. Someone must have told them that that is the easiest thing to screw up, and the easiest to detect, so they were extra careful about that. But then they got sloppy with all the rest of it.
The body of most number/character punches are square. They could have simply clamped down a thick straight edge against the surface, then held the punches tight to the straightedge and that would have kept them all aligned both vertical and horizontal. But that would not have helped with their spacing.
Maybe they surfaced the block, which resulted in the number being ground off. Got it put together and realized the number was gone. And had to put it back by hand, in the cramped space they have right there... ?
