3 Replace the brush. 4 Close the right upper door. 114 Chapter 4 - Printer maintenance EN Cleaning the density sensor Clean the density sensor after replacing the imaging drum and when printed colors are inaccurate. To clean the density sensor and erase lamp 1 Open the right upper door. 2 On the inside of the door, locate the density sensor and the density sensor brush. Use the brush to brush off toner particles from the density sensor and the erase lamp. Note You can also use a hand wipe to clean the density sensor. To prevent scratches on the sensor, do not use any paper products, such as tissue or paper towels, to clean the sensor.