These are the most fruitful avenues I've seen.
I don't think that number was typed. (which doesn't clear up why the final '1' doesn't have any of the imperfections of the others) But if you look at the ones within the body of the form, they are all lower case Ls. (The first typewriter I used didn't have a '1' so this isn't too strange to me.)
ML/NJ
Do the same for the mothers signature. The digital blocks for "(Stanley) Ann D" are one size the blocks for "unham Obabma" are again half the width and height.
Check out the signture of the local registrar. The overall signature is the larger blocks except the seond charater which has the half size blocks.
This can't happen in a single document. The document is composed of material from sources of different resolution.
If you have photoshop, import it at 1200 dpi and the the photoshop grid and addtional magnification will make the differences even more apparent.