Epson 4500 - Manual (Page 197)

Replacing
the Ribbon
7. Use a pointed object, such as a ball point pen, to guide the ribbon
between the print head and ribbon guide while you turn the
ribbon-tightening knob to help feed the ribbon into place. Be
careful not to puncture the ribbon.
8. Slide the print head from side to side to make sure it moves
smoothly. Also see that the ribbon is not twisted or creased.
Maintenance 6-9