Epson DFX-5000 User Manual page 24

6. Insert the ribbon guide over the metal pins on each side of the
print head as shown below. The smaller end of the guide
should be on top, with its angled edge toward the platen. Turn
the ribbon-tightening knob again to remove any slack in the
ribbon.
7. Slide the print head from side to side to see that it moves
smoothly and that the ribbon is not twisted or creased.