Brother HL-4200CN Service Manual page 57

3) Move the side paper guide out so as to align it with the appropriate paper size mark
(A4 in this example).
Note:
Proper guide position differs between A4 and Letter. Align the side guide to the
size mark corresponding to the paper size that you want to load.
4) Grip the end paper guide with your fingers and gently lift it up. Insert the pins at the
bottom of the guide in the holes corresponding to the paper size that you want to
load (A4 in this example).
Note:
Make sure that the end guide is properly inserted into the holes corresponding to
the appropriate paper size.
Only a small amount of movement of the end paper guide can make automatic
paper size detection impossible. If this occurs, move the end paper guide all the
way to its outermost position again, then realign it with the appropriate paper size
mark.
Fig.2-34
Fig.2-35
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