Hello there. I'm afraid none of these stamps stand out as identifiers. Can you send us pictures of the stamps on the balance box? Sometimes how the stamps are printed is just as important as what they say. Also, if the other balance in the window is less worn, that may prove more effective to take pictures from. We'll do our best to narrow this down for you from there.
It's a bit tough to make out, but I agree, it might read as 419--or 4, a # or P, and then 19--which designates the same thing. In that case, you could use a 24-431, which can replace an Andersen sash balance stamped 419. That said, I highly recommend checking another balance, either from this window or from an identical window, to be safe. Let me know if you have further questions.
Hey there, Mark. I agree with my colleague Bob, I think that old stamp reads "4#19." That would make my top pick the 24-431. Just thought I'd offer my perspective, since I happened upon this page!