Canon LBP7660Cdn Manual page 930

If you change the settings, the toner may not fix onto paper well, and the printing may come out
faint.
Select [Curl Correction] under [Special Print Mode] set it to [On] and print again.
"[Setup] Menu ([User Maintenance] Options)"
If you change the settings, the toner may not fix onto paper well, and the printing may come out
Solution 2
faint.
If you specify this setting, printing speed drops.
[Coated 2] [Coated 1]
[Coated 3] [Coated 2]
[Coated 4] [Coated 3]