When i print out a paper, there is a black line through the print out.

I am assuming your black line is printed (not smudged ink)...
If your printer is also scanner/copier, try copying a page (rather than printing from computer).
If it scans & prints ok, it could be communication/driver problem. Try reloading the drivers and see if it improves. If the black line is there when copying as well, there's probably not much you can do about it.

hope this helps
LC
www.inkbank.com.au