When printing on A4, 81/2 inch, B5 JIS size paper and thin paper, you should attach the side plate guides to the side plates of the paper delivery tray.
Using the side plate guides allows you to properly assemble the printed papers on the paper delivery tray.
Side plate guides
Side plate guides come equipped with the machine.
Insert the protruding portion into the side plate holes.
Insert the middle protruding portion first followed by the upper and lower portions.
Turn the side plate guide to the direction shown by the arrow, and make sure it is fixed.
After attaching the side plate guide on one side, repeat the same process for the other side.