To find your Epson maintenance utility: Control Panel\Hardware and Sound\Devices and Printers - then click on your printer, you will see various tabs, one will have a facility to clean your printheads. Using this method does use ink from your cartridges. It will not work if any of your cartridges are empty. Do this procedure a few times and then leave you printer for a couple of hours and then try again for best results.

If your Epson printer won't print a decent "Nozzle Check" without missing lines, head cleanings with the Epson maintenance utility haven't worked and you have tried replacing the offending printer cartridges and the issue still persists even after the new cartridges are installed, you can can be pretty sure you have clogged print heads. 

This is usually caused by not printing often enough and therefore allowing ink to dry in or on the print heads. 

It is important to note that while many printer manufacturers use cheap disposable print heads attached to their printer cartridges, Epson does not. Epson print heads are part of the printer itself which enables Epson to use higher quality print heads with a much better print quality than most similarly priced printers.

While this practice is great for print quality, most long term users of an Epson printer will eventually encounter clogs that can not be cleared by using the standard Epson cleaning utility or by just replacing the guilty ink cartridge.

When this happens you have choices, you can:
1.) Have the printer repaired. This will be almost as or more expensive than buying a new printer unless you have a expensive professional printer.

2.) Replace the print head yourself. This can be very difficult if you don't know what you're doing and almost as expensive as buying a new printer. Printheads are usually as expensive as buying a new printer.

3.) Toss the printer, save the ink and buy a new printer. The best choice for many people if the easier methods of cleaning don't work. 

These procedures are relevant to other brands of printers that use ink-tanks (printheads in the printer and not on the printer cartridge) Brother, HP, Canon, Lexmark, Kodak, Advent
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One of the important aspects to think of when choosing a printer or buying a replacement cartridge, is how much ink or toner that cartridge actually contains. The amount of ink or toner in a cartridge is referred to as the cartridge yield or page yield. 
When you read what the yield of a cartridge is, you will see a number of pages the cartridge is enough to print. For instance, HP CB540A toner cartridge has a declared yield of 2,200 pages, while the Canon PG-540 ink cartridge is capable of printing 180 pages. 
But printed pages differ from one another. For the purpose of cartridge yield measure, almost all printer manufacturers base their black ink/toner cartridge yields on 5% coverage. This means only 5% of the whole page is covered with ink or toner. 5% coverage implies basic type with no bold characters, no graphics and no pictures.
CMYK toners for color laser printers and copiers base their cartridges yields on 20% to 35% coverage (5% to 7% per color). In reality, if a document had a 100% fill, there would be 400% coverage. Tri-color inkjet/toner cartridges base their page yield on 15% coverage (5% per color).

Whatever is the reason for using 5% coverage as industry standard, now you know what it is like and can approximate it for real-life printing.   www.iso.org
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Filling up the page, I repeated the two paragraphs as many as 6 times, which gives us 30% coverage.