Epson EPL-6100 Reference Manual page 224

There may be a problem with
the developer cartridge.
There may be a problem with
the photoconductor unit.
Missing areas on printed image
Cause
Your paper may be moist or
damp.
You may not be using the
correct type of paper for your
printer.
122 Troubleshooting
Turn off the printer. Remove the
cartridge, shake it gently from side to
side, and then reinstall it. If this does not
solve the problem, replace the
developer cartridge as described under
"Replacing the Developer Cartridge"
on page 73.
Turn off the printer. Remove the unit,
and then reinstall it. If this does not
solve the problem, replace the
photoconductor unit as described
under "Replacing the Photoconductor
Unit" on page 80.
What to do
This printer is sensitive to moisture
absorbed by the paper. The higher the
moisture content in the paper, the
lighter the printed output. Do not store
paper in a humid or damp
environment.
If the surface of your paper is too rough,
printed characters may appear
distorted or broken. Smooth,
high-quality copier paper is
recommended for best results. See
"Available paper types" on page 127 for
information on choosing paper.