Apple LaserWriter 360

My Laserwriter 360 prints pages that show a vertical smear that runs the full length of the page. Sometimes, when the printer has been on for a long time the page looks a little cleaner, but generally not. I have looked at the roller and it looks to have smudgey lines on it. Is this a cartridge problem, or something else? If it requires more than cartridge replacement what do I need to remove and clean and what should I use to clean it?
Thanks,
Ken