For some reason, the yellow is no longer printing on my Epson Stylus Pro 10000. I've swapped out the cartridge with another printer and it works fine. Help...

If the yellow is no longer printing, print head nozzle must have clogged. It can be due to using non-epson ink Cartridges or even due to aging equipment.

You can try getting a print head cleaning solution and clean it, but you must do it with great care because the nozzles are very delicate. You can get a cotton ear bud, dip it in distilled water, and clean the gold contacts. Don't forget to switch the power off before doing this. Make sure everything is dry before trying to print again.