Canon iPF780 Series Service Manual page 166

Chapter 4
2) Remove the left/right cover and left/right ink tank cover.
3) Remove one screw [1], and then remove the carriage upper cover [2].
4) Remove the spring [1], release the notch from the protrusion [2] on the side plate, and then remove the linear scale [3] from the left side.
4-40
[1]
[2]
F-4-88
[3]
[1]
[2]
F-4-89