Canon MG6400 series Online Manual page 114

(5) Slide the right paper guide
of the paper stack.
Do not slide the paper guides too hard against the paper. The paper may not be fed
properly.
Note
Do not load sheets of paper higher than the load limit mark (D).
Keep the paper stack height below the tabs
Load small size paper, such as 4" x 6" (10 x 15 cm), by pushing it in all the way
to the back of the feeder.
(A) to align the paper guides with both sides
(E) of the paper guides.
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