You should be able to easily clean the rollers with some iso alcohol and see if that fixes things, or just check the alignment of the smudges and see what it matches as far as pattern of them. Do they line up to where the rollers are?
if the print head can come out clean it and the part with rubbing alc. on some printer you can pick up ink wast and paper under the print head. another issue on some print heads is the rubber o-ring breaks or falls off casing a leak there where the ink tank and print heads connect.