Post mint damage can cause a host of things on a coin....the disappearing 1 was caused by someone who had to much time on their hands ....which caused PMD.
It's post mint damage PMD It was in a welding shop's splatter area. I was welder, and we call some of it bird crap]from your pictures]. Someone, was trying to weld it to something or something near the coin. To weld such, you would need the correct stuff first, which shows, it was not used.
