Problem with printing in black

[krzys27085]

Hello averyone

Last couple days I have problem with printing in black on my M477 FDW. I see some of the lines is missing I have try to diagnose what is wrong but can not recognise the fault. Can anyone help me? Please see attached pictures. I have already replace the black cartridge but problem still exist

[Valsimot]

Looks like a defective black toner cartridge or in the worst case something could be blocking the black laser beam.

[krzys27085]

Yesterday I have istalled new one

[Valsimot · Accepted solution]

If the installed toner cartridge is 100% working and you had the same issue before replacement then it's probably some dirt or something in laser optics that is blocking the black laser beam.

If you remove the toner cartridges inside the printer above cartridges is a laser. A laser assembly has 4 "windows" for each cartridge. There might be some dirt in the black window. Use a cotton swab to clean the black toner window from one side to the other.

[krzys27085]

I have no tray like on your picture, Could you advise me where to clean?

[krzys27085]

Where can I find the laser?

[krzys27085]

Problem solved. Some dirt was in the gap above the cartridge. Printer back to work. Thank you so much for your help