1. The drum potentiometer is not adjusted correctly. Please readjust the drum potential to make sure it is adjusted correctly.
2. The developing bias voltage is not adjusted correctly. Please readjust the development bias voltage to make sure the development bias voltage is adjusted correctly.
3. The drum potential or development bias device is damaged. Please check whether the drum potential and development bias device are damaged, if so, please replace them.
4. Other hardware or software failure. Please check whether other hardware or software is faulty, and if so, please repair or replace them. Canon Inc. (CanonInc.) is a Japanese multinational corporation headquartered in Ota-ku, Tokyo, founded in 1937. Canon is mainly engaged in the development and production of optical, imaging, medical equipment, industrial equipment, semiconductor manufacturing equipment, printers and copiers.