Canon 9192A006 - FAXPHONE L80 B/W Laser Software User's Manual page 51

Do fonts not print smoothly?
Bitmapped fonts designed for dot matrix printers will not look smooth
when printed by your high-resolution printer. Choose another font. Make
sure you install an outline font manager such as Adobe Type Manager or
Bitstream Facelift, or that you choose a TrueType font.
Is the printing not dark enough?
Check the print settings, such as the print resolution, brightness, contrast,
and toner saver. Try replacing the toner cartridge.
Did a toner low warning appear while printing?
If you want to continue printing your document, even though you are
low on toner, change the TONER SUPPLY LOW setting on the printer
from RX TO MEMORY to KEEP PRINTING. (Even if the toner cartridge
is out of toner, the document will not be stored in memory.)
Do vertical white streaks appear?
Vertical white streaks may appear when the error message CHANGE
CARTRIDGE is displayed. This situation indicates that the toner level is
low or that the toner is unevenly distributed in the cartridge.
To resolve the situation, open the front cover of the printer and remove
the toner cartridge. Gently rock the cartridge from side to side five or six
times to evenly distribute the toner inside. Replace the cartridge in the
printer, and close the front cover.
If redistributing the toner does not resolve the situation, replace your
cartridge. For instructions, see Chapter 8 of the Basic Guide.
Chapter 4 Frequently Asked Questions 4-7