Special Notes On Servicing; Paper Feed Motor Adjustment - Canon PIXMA MX870 Service Manual

4-5. Special Notes on Servicing

(1) For smeared printing, uneven printing, or non-ejection of ink
When smeared printing, uneven printing, or non-ejection of ink occurs, print the nozzle check pattern to determine whether the
print head is faulty or not.
< Procedures >
1) Print the nozzle check pattern (in the user mode or in the service mode).
2) If there is a missing portion in the printed pattern, perform the print head cleaning (2 times at the maximum), and print the
nozzle check pattern again.
3) If the problem persists even after the print head cleaning is performed 2 times, perform the print head deep cleaning, then print
the nozzle check pattern again.
4) If the problem is still not resolved, i) turn off the machine and leave it for 24 hours or longer, ii) perform the print head
cleaning, and iii) print the nozzle check pattern again.
5) If the problem still persists after steps 1) to 4), the print head may be faulty. Replace the print head.

(2) Paper feed motor adjustment

1) When attaching the motor, fasten the screws so that the belt is properly stretched (in the direction indicated by the blue arrow
in the photo below).
2) After replacement, be sure to perform the service test print, and confirm that no strange noise or faulty print operation (due to
dislocation of the belt or gear, or out-of-phase motor, etc.) occurs.
The screws securing the paper feed motor may be loosened only at replacement of the paper feed motor
unit. DO NOT loosen them in other cases.
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