If ink spots appear on the back of the page after printing, the printer's interior may be dirty with ink. Perform Bottom Plate Cleaning to remove the ink. To perform Bottom Plate Cleaning, follow these steps:
-
Open the Canon IJ Printer Utility.
-
Under the Cleaning option in the pop-up menu, click Bottom Plate Cleaning.

-
Load paper in the printer
As instructed in the dialog box, fold the A4 size or Letter size plain paper in half lengthwise, and then unfold the sheet.
Load the paper into the rear tray in the landscape orientation with the crest of the crease facing down.
-
Perform the bottom plate cleaning
Make sure that the printer is on and then click OK.
Bottom plate cleaning starts.
PIXMA Pro Series Printers Support