Black ink stopped working on my HP Photosmart 6520

[Paulp16]

I've tried cleaning the printer with Isopropyl alcohol soaked paper towel. No improvement even though this process did help remove substantial amount of black residue.

[Riddle_Decipher]

@Paulp16 Welcome to HP Community! 
HP does not recommend using Isopropyl alcohol for cleaning the device, that said, here are a few steps that should help you resolve the issue: 

Inspect the ink cartridges for clogged vents and for any remaining original packaging.

NOTE: 

Avoid leaving unprotected ink cartridges out of the printer for an extended period of time.

1. Open the ink cartridge access door.

   

2. Press the tab on the front of the ink cartridge to release it, and then pull it out of the slot.

   

3. Examine the vent area on the top of the ink cartridge.

   

4. If the vent is clogged, use a pin to gently remove excess adhesive from the vent.

   1. Clogged vent

   2. Gently remove excess adhesive from the vent

   3. Unclogged vent

5. Make sure the orange pull tab is completely removed.

   

6. Insert the ink cartridge into its slot. Press down until it snaps into place.

7. Repeat these steps for any other ink cartridges with defects on the report.

8. After reinserting all the ink cartridges, run your finger along the top of the ink cartridges. If any are protruding, press down firmly until each ink cartridge snaps into place.

9. Print another Print Quality Diagnostic report.

   • If there are still defects for a specific color bar, replace that ink cartridge. If you have a defective ink cartridge, it might be under warranty. Go to HP Printers - Ink Cartridge and Printhead Limited Warranty for more information.

Let me know how that pans out,

If you feel I was helpful, simply click on Accept as Solution to help the community grow,

That said, I will have someone follow-up on this to ensure you've been helped,

Just in case you don't get back to us within 24 - 48hrs, and have a good day, ahead.