As Kelly pointed out, your nozzle check shows the shades 5 + 6 are switched. If there’s a chance one or more carts were mis-filled, and now that you switched two carts (which the results of wouldn’t show up for several prints and//or cleaning cycles, due to the internal ink lines between carts and the head), you will need to check the individual inks.
You can check ink in carts by doing a Q-tip smear test, and check ink in the printer by printing an Ink Separation chart thru QTR calibration mode.
Instructions for printing the Ink Separation image can be found here: http://www.inkjetmall.com/tech/content.php?144-Print-Ink-Separation-Image-thru-QTR-Calibration-Mode
To test the ink in your carts, shake all the carts, then get 9 Q-tips and a sheet of paper (the best results will be obtained on the print side of a piece of inkjet paper). Place your carts in order from darkest to lightest (following the ink shade placement chart located in your cartridge instructions), and open the fill hole of the first cart. Put a Q-tip up to the fill hole, then tilt the cart so the Q-tip gets wet with ink, and lower the cart. Trying to apply even pressure and make a smooth mark, smear the wet Q-tip across the paper and label it with the cartridge color position. Repeat with other carts using fresh Q-tips, and labeling each mark as you go (and re-insert the cartridge fill hole plug). After all carts have been smear tested, dry the smear test and evaluate the results.
Let me know if you have questions, or what your results are, and we’ll go from there.