Canon DADF-Q1 Service Manual page 58

Chapter 2
b. Sequence of Operation (fax/SEND; double-sided original)
c. Printing (double-side original)
1) The machine picks up the 1st original, and butts its lead edge against the registration roller to remove the skew. (For details of pickup operation, see 'Original
Pickup/Separation.')
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F-2-77