The most common cause for E100 is the drum unit. At the rear of the drum unit should be a small peg pointing into the machine. This gets broken off. It's purpose is to opperate a laser cut off shield when the drum is removed so to prevent laser exposure. If peg is missing laser will not be detected by the system and give E100. Can be repaired or will require a new drum if it has done more than 40 to 60K copies.
Bob, September 2007
