Button sequence for head test (to look for banding)

Turn the printer off.
Load a sheet of white laser paper.
Press and hold the "Power" & "Ready/FF" buttons at the same time.
Release the "Power" button, and keep pressing the Ready/FF" button.
Right after you release the "Power" button, count 4 seconds, and release the Ready/FF" button.
Immediately, press and release the "Ready/FF" button one last time.
The printer should start printing a series of letters, numbers, horizontal lines and a black solid bar at the bottom of the sheet.
Once this test page is completed, turn the printer off to stop the test.