Brother HL-4200CN - Manual (Page 63)

LOADING PAPER AND USABLE PAPER TYPES 3 - 15
8
Align the side guides with the edges of the paper.
Pushing the paper guides too hard against the
edges of the paper stack can cause a paper jam.
However, if the paper guides are too loose, the
paper may twist as it feeds through the printer.
9
Hold the paper tray with both hands as you align it
with the opening in the printer and gently place it in
the printer.
10
Push the paper tray completely back into the printer.
Do not use excessive force on the paper tray. Doing
so could cause damage to the paper tray or the
inside of the printer.
There is an indicator next to the paper tray that tells
you how much paper remains in the tray. Use this
meter as a guide for refilling the paper tray.