6978 won't print black. I've tried cleaning the printhead, contacts, replacing cartridge.

[DH38]

The printer just stopped printing black.  I've tried the printer cleaning tool.  I've tried cleaning the contacts.  I've even replaced the cartridge (which was relatively new).  Nothing seems to work.  This "Virtual Agent" suggests taking off the printhead and using hot water, but it doesn't appear that the 6978's printhead HAS a "release lever."

[sandytechy20]

@DH38

Welcome to the support community.

Make sure the ink cartridges are properly vented and seated correctly

1. Turn on the printer, if it is not already turned on.

2. Open the ink cartridge access door.

   The carriage moves to the center of the printer.

   

3. Wait until the carriage stops moving before you continue.

4. Press the tab inward on the front of the old ink cartridge to release it, and then pull up on the ink cartridge to remove it from the slot.

   

5. Examine the vent area above the HP logo on the top of the ink cartridge.

   

6. If the ink cartridge still has the orange pull-tab attached, pull to remove it.

   

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

8. 1. 

      Clogged vent

   2. With a straight pin, gently remove excess adhesive from the vent

   3. Unclogged vent

9. Turn the ink cartridge so that the ink cartridge contacts face downward, and then match the label color with the color dot on the carriage.

10. Slide the ink cartridge into its slot, and then gently press the ink cartridge down until it snaps into place.

    

11. Repeat these steps to inspect the vents on each of the ink cartridges.

12. Make sure each ink cartridge is firmly installed in its slot. Run your finger along the top of the ink cartridges to feel for any that are protruding, and if any are, press down firmly until each ink cartridge snaps into place.

13. Close the ink cartridge access door.

    

14. Try to print.

You can refer this HP document for more assistance:- Click here

I hope that helps.

To thank me for my efforts to help you, please mark my post as an accepted solution so that it benefits several others.

Cheers.