After a certain number of uses, the Epson R300's waste pad will inevitably fill up completely with ink, and you will be forced to clear it before you can resume printing. The printer's internal counter will alert you when the waste pad begins to overflow via a "Service Required" message on the printer's screen. After you've cleared out the ink, the counter must be reset.
Turn on the Epson R300 by holding down the "Power" button until the printer's screen comes on.
Hold down the "Power," "Stop" and "Maintenance" buttons simultaneously for 10 seconds, until a message appears on the screen indicating that the counter is being reset. You will then be prompted to power down your printer.
Turn off your printer and unplug the power cord. Wait for one minute before plugging the cord back into its outlet and powering up your printer.