Epson 4500 - Manual (Page 31)

Assembling the Printer
Install the ribbon cartridge as follows.
1. Slide the print head to the middle of the printer.
CAUTION:
Never move the print head while the printer is
turned on because this can damage the printer. Also, if you
have been using the printer, the print head may be hot; let it
cool for a few minutes before touching it.
2. Turn the ribbon-tightening knob in the direction of the arrow. This
removes slack in the ribbon and makes it easier to install.
Setting Up the Printer 1-9