Most printers (Canon, H.P., etc) have the print head on the actual cartridge so that when you change the cartridge you get a new print head, whereas some Epson printers have a print head built in to the printer itself and separate from the ink cartridge. When this Epson print head gets blocked, a new cartridge won't make any difference until the built in print head gets cleaned.
Never had an Epson myself for that reason and I think that's where your problems start. Printing a small coloured picture every 7 to 10 days should keep any print head clean and the ink flowing freely otherwise the ink tends to dry out a block the tiny holes in the print head.
It all depends on whether you can strip the Epson down and get to the print head to clean it.