Canon imagePRESS C1+ Reference Manual page 259

11
Fasten the black adjustment screw on the left using a coin or
something similar while slightly pressing the outer size change plate
against the paper stack.
12
Similarly, fasten the black adjustment screw on the right using a coin
or something similar while slightly pressing the outer size change
plate against the paper stack.
Make sure that the two black adjustment screws are fastened securely.
13
Remove the second stack of paper, such as A4 paper if you have
loaded next to the first stack of paper.
Adjusting the Machine
4
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