Yellow prints out green or White Ink looks muddy or grey.
REASONS AND SOLUTIONS:
1. Other colors of ink have back-flushed into the yellow damper
**Run several head cleanings using the Ink button on the control panel. This will flush out the contaminating colors.
Prevention: After filling all the ink colors set all valves to draw ink. Press and hold the Ink Fill button for 5 - 10 seconds. Run several head cleaning cycles after that.