Line down the middle of the page when I &qu...

This has only been happening for the last few days with my HP Officejet J5780 All-in-One scanner/copier/fax machine.

I can "print" documents just fine, with no extraneous line down the middle of the page (top of the page to the bottom, right down the center). But once I stick the same page in the automatic feeder to be copied, every page gets a line down the middle of the page. Some pages get two lines, about an inch and a half apart.

I remember about ten years ago when I had to clean the "heads" of a copier or printer when this happened. Can I clean the heads (or whatever it is, now) with this one? If so, how do I do it?

Thanks for your help.