Looks like some sort of chemical process has "moved" or dislocated the numbers as well as rendering some out of shape...I see what looks like an 8 or maybe a 3 as the 4th number, but it's now up above where it should normally be...rules out the 1909. Third place number not a 0 but maybe what's left of a chemically mutilated 1 or 2...my best try, no way to know for sure.
Searching through my old posts, a little over a year later. I was searching myself, and think I may see a one, though slightly distorted by one of those bubbles. I'll show what I see, what do you think? Looking at the placement, it seems like it's in the right place. I'm pretty certain that's a one peeking up over that bubble. In the question of serifs, they are certainly on that S. Funny thing is, can't find the coin now. When I get home I'll have to search my room for this and some folders I lost.