DIAGNOSIS That's clogged print head nozzles, not bad ink. The pigment black ink in these models is especially prone to drying if the printer sits unused for a few days.
FIX Run the printer's built-in head cleaning utility. On the control panel, press the Home button, navigate to Settings > Maintenance > Print Head Cleaning. Run it once, then print a nozzle check pattern (also in Maintenance). If lines are still missing, run the cleaning cycle one more time. Wait a few minutes between cycles.
IF THAT DIDN'T WORK For a more powerful clean, use the 'Head Cleaning' option from the Epson Printer Utility software on your computer, not just the panel. It can sometimes run a more intensive cycle.
HEADS UP Head cleaning uses a lot of ink. Don't run it more than twice in a row. If it's still clogged after that, let the printer sit for a few hours—sometimes the ink needs time to rehydrate the clog.