Epson EPL-N2750 Quick Reference Manual page 19

The printer cannot print at the requested quality level
because of insufficient memory, and the printer reduces
the quality automatically so that it can continue printing.
Check to see if the printout is acceptable. If not, add more
memory (for a permanent solution) or temporarily set
the Print Quality setting to Low in the printer driver.
The imaging cartridge is not correctly installed. See
"Replacing the Imaging Cartridge" on page 26 to
reinstall it.
An interface card not supported by this printer is
installed. Turn off the printer, then remove the card.
A hard disk drive that cannot be used with this printer
is installed. Turn off the printer and remove the drive.
An option not supported by this printer is installed, or
a supported option is installed incorrectly. See "Using
Options" in the Reference Guide to make sure you are
using options made for this printer or to reinstall the
options.
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