Canon iR4570 Series Service Manual page 720

14.2.1.3.3 Black Dots
0007-7093
iR2270 / iR2870 / iR3570 / iR4570 / iR3530
<Cause>
On some types of paper (especially those with a high calcium carbonate content), toner offset to the fixing film can
start to cake, moving from the fixing film or the pressure roller to the face or back of paper.
<Field Remedy>
Use the following service mode item to change the timing at which the fixing pressure roller is cleaned:
COPIER>OPTION>BODY>FIX-CLN
0: disable cleaning (default)
1: execute cleaning during last rotation every 500 printouts
2: execute cleaning during last rotation every 200 printouts
3: execute cleaning during last rotation every 100 printouts
<Image Sample>