The following causes can be considered.
Solutions
Make sure the paper type in the printer settings matches the actual paper type.
List of Paper Type
When printing on plain paper,use a higher quality setting.
Windows
Select High from Quality on the printer driver's Main tab.
Mac OS
Select Fine as Print Quality from the print dialog's Print Settings menu.
Select the Maintenance > Print Head Alignment > Horizontal Alignment menu on the control panel to align the print head.