Printer Prints Half of Page

[John Doe 57]

My HP Officejet 6310 All-in-One Printer only prints about half of a page. The ink begins to fade around 25% complete and at 50% complete, the ink is non-existent. The first 25% come out great showing no fading.

I know for a fact that the ink is not low because the printer will let me know when to replace the cartridges. When I thought that maybe the printer didn't know if the ink was low, I bought some more cartridges. That didn't help because even with brand new cartridges installed, the printer still prints only half of the page. I've aligned the cartridges and cleaned the cartridges but it hasn't helped. Any solutions?

Thanks.