Epson CX6500 Reference Manual page 236

Make sure that the CX6500 is on and the ! Error light is
off.
Access the printer
software.
Accessing the Printer Software for
Windows
Click the Maintenance tab, then click the Head Cleaning
button.
Follow the on-screen
instructions.
Head cleaning... appears on the LCD panel while the CX6500 performs the cleaning
cycle.
Caution:
Never turn off the CX6500 while Head cleaning... appears on the LCD panel. Doing so
may damage it.
When Head cleaning... disappears from the LCD panel, click Print Nozzle Check Pattern in the
Head Cleaning dialog box to confirm that the print head is clean.
Good: print head does not need to be cleaned yet.
Not Good: print head needs to be cleaned.