Epson TM-T88II Series Operator's Manual page 31

If there is no paper jam and the printer has been printing for quite a
while, the print head may be overheated. If the print head is
overheated, the printer will resume printing when the head has
cooled (usually within two or three minutes).
If there is no paper jam and the print head is not overheated, turn
off the printer and turn it back on after about 10 seconds. If the
ERROR light is still flashing, contact a qualified service person.
The ERROR light is off, but nothing is printed.
Try to run the self test to check that the printer works properly. See
the self test instructions in Chapter 1 to run the self test. If the self
test does not work, contact your dealer or a qualified service
person.
If the self test works properly, check the following:
1. Check the connection at both ends of the interface cable
between the printer and the computer. Also make sure that this
cable meets the specifications for both the printer and the
computer.
2. The data transmission settings may be different between the
printer and computer. Make sure that the printer's DIP switch
settings for data transmission are the same as the computer's.
You can print the printer's interface settings using the self test.
If the printer still does not print, contact your dealer or a qualified
service person.
Printing is poor.
Paper dust on the heating element of the thermal print head can
lower the print quality. Try cleaning the print head as described
below:
3-2 Troubleshooting