Canon Color imageRUNNER LBP5975 User Manual page 358

If the levers are not in the proper position, the drum cartridges cannot be
installed. Raise the levers to the proper position as shown in the figure.
- Incorrect position - Correct position
9
Install the drum cartridge in the printer.
Insert the drum cartridge firmly until it touches the back of the printer.
6
Replacing Drum Cartridges 6-35