missing black colour in print quality diagnostic report but has black text

[chrisy_lo]

Black is not printing normally - most of the time black text are printed in navy blue, but sometimes it prints in black.

Here is the Print Quality Diagnostic Report - all the text and borders are printed in black, but the box for black that supposed to have shades of black colour (first box in section 3) is empty, though it has black borders. 

So far have tried:

- Have installed new printer driver, firmware is up to date.

- Ink is new.

- Have checked the cartridge's vent and appears ok.

- setting it to print as photo.

Please help!

Thanks.

[8lives]

The black printhead is most likely clogged.

You can try cleaning it manually using info from youtube.