A:
The drum is what transfers the image to the paper. Not to be confused with the individual toner cartridges (black, cyan, magenta and yellow) which are separate and unique items. You do not need a drum unless it is time to replace it (images not transferring correctly, or as in my case, a dark line down the side of all printed pages). In my case, I am just having to replace drum for the first time after 5 years of moderate to heavy use.
Answered on 5/5/2010 by girlbot from san diego, CA