Canon multipass c3000 Service Manual (en)

6.2.5 PRINT test
Pressing the 
button from the test mode menu selects the print test.  This test prints
various patterns.  For servicing, use the 3-7: CHECKERS pattern (press the 
button from
the print test menu).  The other patterns are not to be used since they are for development
and factory personnel.  End this test by pressing the STOP button.
Check the pattern for the following:
If the print test is normal, make a copy of a document.  If the copy is faulty,
the reading section is faulty.
Chapter 3: Maintenance & Service
Check for any vertical or horizontal white 
stripes on the black squares.
Also, check that all the squares have 
straight edges on all four sides.
Figure 3-28 Print Test Pattern Check