I may get scolded by some repair techs, but I have found it useful to squirt WD-40 into a dot matrix printer ribbon to extend its printing darkness. Not _too_ much, mind you, just a gentle dampening of the ribbon.
I find that most dot matrix printers print in the center portion of the ribbon, leaving alot of space above and below that is not used. The ink in those locations dries up and/or just sits there. If I put a small amount of WD-40 on the ribbon, the ink dissolves into the WD-40 and spreads into the printable area of the ribbon. Then the WD-40 dries up and the ribbon works well. If you put too much WD-40 the print will get a little fuzzy because the ribbon is over wet, although it is still legible. Hmm maybe poor man's antialiasing.
The worst part is finding a spot on the cartridge where to stick the little red tube to evenly coat the ribbon. However I think on the 10X it uses little spools of ribbon, which makes it easy.
I am sure this approach would work for re-inking as well with real ink, assuming you can find a compatible ink. Over application would probably still be an issue.
Another trick for the 10X might be to "flip" the ribbon over if the printed area is off center, causing the printer to print on a fresh area of the ribbon. You might have to despool the ribbon to do this, which could be messy, and this assumes off center printing.
