Aligning the Print Head
If your printouts contain misaligned vertical lines, or you see white or black horizontal banding, you may need to align the print head.
Note: Your printer must be connected directly to your computer (not over a network) to use the Print Head Alignment utility.
1.Turn on the printer.
2.Load plain,
3.Windows: 
printer icon on your taskbar (in the lower right corner of your screen) and select Print Head Alignment.
Macintosh OS 8.6 to 9.x: Choose File > Page Setup or Print. Click the
Utility button, then click the 
Print Head Alignment button.
Macintosh OS X: Open the Applications folder and select EPSON Printer Utility. Select SP820 Series in the printer list, click OK, and select Print Head Alignment.
4.Follow the instructions on the screen to print a test page. You see this window:
5.On the test page, select the pattern with the two vertical lines most precisely printed on top of each other. You may need to use a magnifying glass or loupe.
Select one pattern each for rows 1, 2, and 3. Then enter the number of the best pattern for each row in the corresponding boxes on the screen. Then click Finish.
If you can’t find an aligned pattern, click Realignment to print another test page, then repeat this step.
Maintaining Your Printer 39