Epson TM-U200D series Operator's Manual page 23

Note:
Make sure that the ribbon is installed between the print head
and the platen without wrinkles or creases.
4. Turn the ribbon cassette's knob 5 or 6 times in the direction of
the arrow again, to take up any slack in the ribbon.
1–12 Setting Up the Printer
* The shape of the
print head may be
different from the
illustration.