When printing a few lines are printed then the next few are offset then the next are further offset and so on untill the carriage jam fault is indicated. lines across the page are ok its the vertical lines that are offset. When the printing stops there is a noise like a gear turning and the teeth comming in and out of mesh, ratcheting.

Lindsay, May 2011

Not so easy to pinpoint the problem remotely.
You should be able to get repair manuals for your model from the HP website. If not, do a Google search.
HP printers are usually quite easy to work on.

Munro, May 2011