There are two places for replacing the pickup rollers: on the back of the printer (two rollers) and on the paper cassette (one roller).
Turn off the printer by pressing the 
button, and then unplug the power cord.
Remove the new pickup rollers from their package.
The pickup rollers for the paper cassette 1 and paper cassette 2 to 4 are different. Check the direction of arrow on the center of the pickup rollers, and make sure the pickup rollers are the ones for paper cassette 2 to 4. If you attach the wrong rollers, the printer may not feed the paper.
Be careful not to stain the surface of the pickup rollers. If the dust collects on the surface of the pickup rollers, clean the rollers by using a soft and moist cloth. Using a dry cloth may damage the surface of the rollers.
Pull out the paper cassette for which you want to replace the rollers.
Turn the printer around, and then open the printer's rear cover.
Remove the screws by a screwdriver and remove the cover on the rear of inside the printer.
Slide out two used pickup rollers, and remove both of them.
Insert two new pickup rollers until they click into place.
Insert the pickup rollers by rolling them so that you can insert them smoothly.
Fasten the screws to reattach the cover.
Close the rear cover.
Release the lever.
Slide the pickup roller toward the lever, and then remove them by taking the shaft out of the holder.
Insert the shaft of the new pickup roller into the hole in the holder, and then slide the shaft on the lever side along the slot while it is facing the flat surface at the front.
Lock the lever.
Insert the paper cassette.
Turn on the printer, select Settings > Maintenance > Pickup roller information > Reset Counter, and then select the paper cassette in which you replaced the pickup rollers.