Dell 5110cn Color Laser Printer - Manual (Page 313)

3.
Cleaning the Automatic Density Control (ADC) Sensor
CAUTION: Before performing any of the following procedures, read and follow the safety
instructions in your Owner's Manual .
CAUTION: Do not touch the edge of the plate at the upper side of the transfer roller
because it is sharp.
When the printer's automatic density control (ADC) sensor is dirty, follow the procedure below to clean it.
Turn off the printer. 1.
Push the front latch up and fully open the front cover. 2.
Grip the tabs at both ends of the transfer roller and gently lift it out of the printer. 3.