All inks are full and working fine except black.

This is a common problem with Epson printers. Since your printer uses DuraBrite Ultra ink the problem is the OEM Epson ink is rather thick and tends to clog the printhead. Epson pigment ink has been like this for years.

Anyway the printer you have isn't a wide format model so I wouldn't take it to a printer shop to have it unclogged. For yours, I'd just buy the Epson printhead cleaning fluid kit and unclog it yourself. Many vendors sell it in kit form and it's commonly found on eBay. If this doesn't work it's either a problem with the printhead or air.

If it's an air problem, inject compatible ink into the printhead directly. DO NOT USE GENERIC PIGMENT INK. THIS CAN DAMAGE THE PRINTER. Again, find a compatible ink from someone but buy it from a Epson refill specialist to avoid buying incompatible ink that will damage the printhead.

After you fix it, keep a 4 color test document consisting of the word TEST in all 4 colors. This will keep the ink flowing if you print it at least once a week (at least every 3 days in humid climates). You can also use the nozzle check as well, but that requires the Epson toolbox on a PC.