You must start the drum unit replacement procedure by opening the front cover of your monochrome laser printer. The complete drum unit replacement procedure is included below. 21degreesC/70degreesF with a relative humidity of approx.

It is always better if you keep a spare/new drum unit for your Dell Black & White 1720DN laser printer in stock, but please store this consumable component on a pallet or shelf (not directly on the floor), where the temperature is approx. You must install a new drum unit, in order to be restored the normal functionality of your monochrome laser device.  The and the LEDs are blinking – This signal indicates a non-operational mode caused by a completely exhausted drum unit, which means that you won't be able to complete your current task or to print new documents. You should install a new drum unit soon after the initial appearance of this signal, in order to avoid a variety of print quality issues, such as background fogging, blurred images, blank copies, solid copies, white banding, and/or black banding.  The LED is blinking – This signal indicates a nearly exhausted drum unit.  The overall print quality is gradually decreasing and/or there are constantly reappearing print quality issues – The installed drum unit is at the end of its useful life, and it needs to be replaced soon. These signals/signs are listed and described below. There are three signals/signs, which are indicating an exhausted drum unit in your monochrome laser printer. Therefore, the built-in system is constantly monitoring the status of the installed drum unit, and it will notify you when this consumable component is near or at the end of its useful life. The drum unit installed in your Dell Black & White 1720DN laser printer is an important consumable component, which must be replaced before the complete exhaustion of its print resource.

Dell 1720dn laser printer system