Canon DR-2050C Startup Manual page 69

4
Shift the Retard Roller to the left to separate it from the shaft, and then
remove it.
Attaching the Retard Roller
1
Position the retard roller so the notch in the roller is facing the scanner's shaft.
2
Slide the roller lock lever to the right, and then insert the shaft into the hole on
the left side of the Retard Roller.
Regular Maintenance
65