Epson LQ-300 User Manual page 72

If the top or bottom edge of the characters in the self test are a
different color from the rest, adjust the ribbon angle with the
color ribbon adjustment lever. See page 3-12 for details.
Note:
When your print using the color ribbon, print speed my be reduced.
To switch to the black ribbon, remove the color ribbon and then
install the black ribbon as shown on page 1-6. To remove the
color ribbon, press down on the motor unit and pull out the
cartridge as shown below. You do not have to remove the
motor unit.
2-38 Using the Printer