If all of the above doesn't work, clear print head cartridge path, normal paper path, no broken pieces then I usually do a maintenance kit and change out all the rubber pick ups, etc.
sometimes some of mine make wierd crunching noises when they are struggling to pick up paper. If you need to wait for the kit in the mail then I've put lots of paper in to alleviate, when paper gets low sometimes it makes that noise if the pickups are old
