Epson TM-C3400 Technical Reference Manual page 142

3
Pull out the empty ink cartridge to remove it.
Do not leave the printer without ink cartridge.
Otherwise, the print head may dry and clog.
CAUTION
4
Shake new ink cartridge package 4 or 5 times before opening it and
take out the ink cartridge from the package.
5
Push the ink cartridge gently into the cartridge holder as shown below.
Insert it with arrowed side up.
6
Close the ink cartridge cover.
The INK LED (red) turns off.
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