Why is my HP Photosmart 6520 not printing black?
Printhead cleaning is the most effective solution for unsatisfactory prints, especially streaky or missing black or colors. Use a Print Quality Diagnostic report to check if the printhead needs to be cleaned or if there is an ink cartridge alignment issue. Load plain white paper in the tray.
How do I clean the printheads on my HP PhotoSmart 6520?
Touch Settings , touch Tools, and then touch Clean Printhead. If print quality is unacceptable on the page that prints, touch Clean Again to perform a second cleaning, and then continue to the next step. If there are defects in the alignment patterns, align the printhead.