Select System Preferences (or System Settings) from the Apple menu > Printers & Scanners (or Print & Scan or Print & Fax) and then select the printer.
Click Options & Supplies > Utility > Open Printer Utility.
Click Power Ink Flushing.
Follow the on-screen instructions.
If all nozzle check lines are still not printed completely after running Power Ink Flushing, contact Epson support.