Tente verificar / reparar / substituir o obturador laser e seu braço de atuação.
The laser shutter is a metal flap that covers the laser porthole when the cartridge is removed as a safety interlock. The porthole is a slit of about 1/2 by 3 inches in the back of the cartridge compartment (if you open the cartridge compartment, the front will be toward you.)
The locking mechanism seems to wear out easily, and the laser shutter fails to open even with the cartridge is inserted. The problem sometimes goes away if you reinsert the cartridge, but eventually it becomes permanent.
You can pry the flap open with a small screwdriver but do it at your own risk; the flap is a safety interlock to prevent the laser light from exiting the cartridge chamber when the cartridge is removed.
Exemplo de imagem do braço do obturador a laser:
Citaraqui:
Mais informações / sugestões sobre como lidar com um obturador defeituoso aqui: Canon mf 6550 cópia sem impressão sua saiu página vazia