Not sure how Marlin does it, but I got a used 39A that the gold lettering was a bit faded, I used a yellow paint marker made by Faber Castell, oil based fine line, basically traced over the lettering and wiped off the excess. I made sure I cleaned and degreaser the worn lettering first.
So far it seems to be holding up very well, I compared it to another model 39 and you can't tell the difference.
So far it seems to be holding up very well, I compared it to another model 39 and you can't tell the difference.