Canon LBP7210Cdn Manual page 469

"Loading Custom Size Paper (Non-Standard Size Paper)"
The toner cartridge has run out of toner, has deteriorated, or is damaged.
Cause 2
Solution Check the status of the toner cartridges.
Replace the toner cartridge that is almost empty with a new one.
"Checking the Printer Status Using the Printer Status Window"
"Replacing Toner Cartridges"
The drum in any of the toner cartridges has deteriorated.
Cause 3
Solution Replace the toner cartridge with a new one.
"Replacing Toner Cartridges"
Colors Are Uneven or Not Printed Smoothly
Large characters, wide lines, or diagrams with high color density were printed.
Cause
Solution Perform the following procedure in the printer driver.
1. Display the [Finishing] sheet.
2. Click [Advanced Settings].
3. Select the appropriate mode for [Special Smoothing Mode].
Normally, select [Mode 1] for [Special Smoothing Mode].
If the following conditions occur when [Mode 1] is selected, select any setting between
[Mode 2] and [Mode 6].
If gradations cannot be printed smoothly
Select
If the following problems occur at the same time
Gradations cannot be printed smoothly.
The areas around large characters or thick lines (especially those with low
color density) are not printed smoothly.
Select
If the areas around large characters or thick lines (especially those with
low color density) are not printed smoothly
Select
If strip-shaped unevenness appears on gradations
[Mode 2].
[Mode 3].
[Mode 4].