Epson LQ 630S Reference Manual page 70

There is too much slack in the
ribbon or the ribbon has come
loose.
Lines of dots are missing in the printout as shown below.
Cause
The ribbon cartridge is not
installed correctly, and the
ribbon is twisting or
slackening.
The print head is damaged.
The characters are shortened vertically or the line spacing is
entirely closed.
Cause
The proper setting has not
been made for the multipart
forms with cut-paper tab
binding.
64
Troubleshooting
Remove any slack in the ribbon by
turning the ribbon-tightening knob, or
replace the ribbon cartridge as described
in "Replacing the ribbon cartridge" on
page 118.
What to do
Stop printing and reinstall the ribbon
cartridge as described "Replacing the
ribbon cartridge" on page 118.
Stop printing and contact your dealer to
have the print head replaced.
Warning:
w
Never try to replace the print head
yourself because other parts of the
printer must be checked at the same
time.
What to do
Set the multipart forms with cut-paper
tab binding setting in the default-setting
mode to on.