Brother MFC-8420 User Manual page 175

4
When loading paper in the MP tray, make sure it touches the
back of the tray.
Make sure that the paper is straight and in the proper position
on the MP tray. If it is not, the paper may not be fed properly,
resulting in a skewed printout or a paper jam.
5
While pressing the paper-guide release lever, slide the paper
guide to fit the paper size.
When you put paper in the MP tray, please remember the
following:
The side to be printed on must be face up.
During printing, the inside tray rises to feed paper into the
MFC.
Put the leading edge (top of the paper) in first and push it
gently into the tray.
6
Send the print data to the MFC.
11 - 7 USING THE MFC AS A PRINTER
Paper-guide
Release Lever