Canon imageRUNNER ADVANCE C5000 Series Technical Workbook page 228

BK
[Reference] To ensure that the toner supply mouth has been pushed in until it stops,
check that the line [A] on the pipe of the hopper unit (Bk) and the line [B] on the
toner supply mouth are aligned with each other.
24) Assemble the parts in reverse order from step 23) to 1).
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