Canon TR7660 Online Manual page 531

Insert the transport unit cover slowly all the way into printer and take down the transport unit cover.
6. Attach rear cover.
Insert the projections of the right side of the rear cover into the printer, and then push the left side of the
rear cover until it is closed completely.
7. Plug in the printer again and turn it back on.
All jobs in the print queue are canceled. Redo the printing.
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