before you remove old ink, please print an image and see how the image looks; then please does a nozzle check up; Now you can remove the old ink and purge all the ink out from both ink tubes and print head; then you can put our ink on, press purge button and pause for the air to come out, continue to purge and pause for air to come out. Then wait for about 20 min before printing. In the beginning, the print out may not look good as it takes a little time for the print head to heat up. You can also adjust the negative pressure if necessary.