Press the panel buttons in the following sequence:
Main power on, front panel power off. Press the panel buttons in the following sequence:
Down, right, left, up, right, down, left, press and hold right, left, and down buttons all at once and turn on front power while holding those buttons down. You can let go of the buttons after a couple of seconds. This must be down fairly quickly. If you get an error message about service mode, try again. Once successful, when you press the menu key you should see menu and service menu as choices. Setup sheet, do a nozzle test print. Then press the menu key, right arrow into service menu, right arrow into print menu, down arrow to test pattern, right arrow into test pattern, down arrow to fill and press enter. Watch how it prints, noting how the passes look and look for gaps in the passes. During printing, also watch the edges on both side of each color band. The edge of each pass should line up with the previous pass. If the edges of a color is stepping back and forth while printing, the bidirectional is off in that color. Also the edges should be very clean and crisp. Look for any overspray or steaking on the edges. This test will give you a lot of feedback about the condition of each color channel. If you post pictures of the nozzle test print and pictures of the edges of the fill test, it will be very helpful for the people here help you determine what is wrong and what to do to fix the issue.