Canon imageRUNNER ADVANCE 4551i Service Manual page 325

When Check with the Paper
1. Check the rear-left height of the DADF.
Cut a sheet of paper to make a paper slip with width of 45mm. Set paper against the protrusion in such a manner that the
sheet is nearly hidden, and then close the DADF.
NOTE:
By placing the paper slip as instructed, it does not interfere the soundproofing sheet stuck on the bottom of the DADF when closing
it.
CAUTION:
Use plain paper.
Set paper so that it does not reach the document reader.
Soundproofing Sheet
Paper
312
5. Adjustment