Canon iR C6800 Series Service Manual page 879

13.2.6 Grid (TYPE=6)
Use this text print to check color displacement, right angles, and straight lines.
a. Color Displacement
If color displacement is found, suspect a scar in the ITB and a fault in the drum unit.
b. Right Angle, Straight Lines
If the right angles or straight lines are not correct, suspect a fault in the laser exposure system, a fault in the shape of
the registration (middle/outside) roller, and a fault in the secondary transfer outside roller.
F-13-3
Chapter 13
0001-6117
13-7