There are three kinds of rollers.
Pick-up roller
Pulls the paper out of the tray and feeds it to the feed roller.
Feed roller
Feeds the paper from the tray into the paper path.
Separation roller
Rotates with the feed roller. However, if more than one sheet of paper is fed, a torque limiter clutch reverses the rotation of the separation roller, sending the paper back into the tray.
ADF
Separation roller
Pick-up roller
Paper feed belt
Trays 1-3
Feed roller
Pick-up roller
Separation roller
Paper feed rollers of the Optional Feed Roller Unit are also needed to be replaced if it installed. Replacement instructions is the same as how to replace the rollers of tray 2-3.
Multi bypass tray
Pick-up roller
Feed roller
Separation roller
Tray 4 (LCT)
Pick-up roller
Feed roller
Separation roller