Tektronix Z740/N - Phaser 740 Color Laser Printer Service Manual page 118

Single light, horizontal line in all the
prints
This is probably caused by a defective
photoconductive belt onto which toner will
not transfer. Replace the imaging unit.
Large, random light smudges
Spots such as those illustrated are caused
by fingerprints on the photoconductive or
accumulator belt. Often, the smudges will
gradually fade with additional printing.
Alternately, the imaging unit will have to be
replaced.
Fingerprints can be removed by applying
some toner (any color) to the fingerprints
and rubbing lightly with a cotton-tipped
swab. Don't remove the toner. The printer
will remove the toner with its cleaning blade.
Remember not to expose the imaging unit to
ambient light for more than a minute.
107
Service Guide