Apple LaserWriter 12/640 PS - Manual (Page 234)

The page prints solid black.
If your document prints black, turn your printer off and on again. If your
document still prints black your printer needs servicing.
Printer prints simplex even though duplex printing is specified.
If your document prints in simplex mode (only on one side) instead of duplex
mode, check the following:
m Is the optional duplex printing unit installed?
m Does the printer have at least 12 MB of memory?
m Is duplex printing selected in the Print dialog box?
Unwanted lines or stripes appear.
If white or dark vertical or horizontal lines or stripes appear on the page, try
the following remedies. (Each procedure is described in detail in “Replacing
the Toner Cartridge” in Chapter 10.)
m Gently rock the cartridge to redistribute the toner.
m Replace the toner cartridge.
m Clean the mirror by sliding the yellow plastic square back and forth to
remove any toner residue.
The image is wavy or distorted.
If a gray shaded area appears wavy or distorted, the toner cartridge may be
low, or the toner may need to be redistributed (see “Replacing the Toner
Cartridge” in Chapter 10).
Toner smudges appear on front or back of paper.
If stains appear on the paper, try the following steps.
m Toner smudges may occur after a paper jam. In most cases, the printer
cleans itself after printing several letter-size pages.
m You may have previously printed using paper that was too small for the
printed document, which may have caused some toner to be deposited
inside the printer instead of on the paper. This can cause smudges on the
paper that goes through later. In most cases, the printer cleans itself after
printing several letter-size pages.
235 Fixing Paper and Image Problems