Canon Pixma MG6450 PGBK Ink Printing blurred/shadowed, is there a fix?

The black PGBK ink on my Canon MG6450 is printing shadowed text whilst all other colours are working fine. I've tried all cleaning settings from the printer and changed the ink cartridge as well but no luck.

Has anyone else faced similar issues and, or knows of a fix? I have attached a image for reference.