See Service Sheet. Scratched, Nicked, or Pin Holed Drum Replace or Call Service Tech. Uneven Toner Concentration Call Service Tech to repair. Exposure Lamp has Blackened Cell Replace or Call Service Tech. Canon NP Series Copiers do not use developer.
Units do however.
Diagnosis of Spots or Marks on Copy Regarding Spots, Marks, etc. Run 3-5 copies of an original. If the imperfection on the copy stays stationary on each copy during multiple copy runs, the problem can be pin pointed to dirty copyboard glass or dirty optics. Look at your copyboard real close, for any small residue on the glass will leave a subsequent black mark on your copy. With a imperfection on the problem roller that imperfection will be reproduced on the copy equal to the circumference of the damaged drum or roller.