This is a follow-up to my original message. I'm having better luck refilling Lexmark Z51 cartridges. Eventually the ink will stop running out.
Final wipe is with the cartridge upside down.
Check with a magnifier that the nozzles are clean. If that doesn't bring the color back, inject some clean color until a little runs from the nozzle, and repeat the above wicking procedure. It's tricky but eventually the cartridge should be back to normal.