Black print quality bad after third level diagnostic cleaning

[TAL12]

Print quality for black ink leaves a consistent single line of no ink across page every inch or so down the page. Ran Print Quality Diagnostic through the third level cleaning, at which point it says contact technical support. The HP 64xl black ink cartridge is only a couple months old, still about 80% full. I am guessing this is a cartridge problem, but wanted to see if there is any feedback on this issue before I go buy another new cartridge. Thanks! 

note: the tri-color cartridge prints colors perfectly well.

[Bob_Headrick]

It sounds like you have already done the troubleshooting steps without resolving the issue.  There are a couple of additional things you could try before replacing the cartridge:

• Clean the cartridge and printer's electrical contacts as shown in step 3 of the document here.  (Click on the "Type 1..." line to expand the items.
• If the above does resolve the issue try the following:  get a coffee cup and put 1" of hot, but not boiling, water in the cup.  Put the cartridge in the cup with the nozzles facing downward (in the same orientation it would be in the printer).  Let the cartridge soak for fifteen minutes, then remove the cartridge and gently blot the nozzles on a damp tissue.  Dry the electrical contacts with a lint-free wipe (a clean coffee filter works well for this).  Put the cartridge back in the printer and try printing your sample. 

If all the above does not resolve the issue I would suggest replacing the cartridge.  HP cartridges do have a warranty, see the document here for information. To get warranty coverage you will need to go to the Contact HP page, then enter the information for your printer.  At this point it will likely say "Manufacturer's warranty has expired" (for your printer).  To the right of this it will say "See details".  Click the "See details" link, which will open another page with more details.  Near the bottom of the text will be a paragraph that says: 

HP has checked your product information, including the product and serial numbers, to determine your warranty results.The legal warranty expiration date is based on the date of purchase, as indicated on your receipt. If you feel these results are incorrect, you may submit a dispute for review. Dispute this > 

Click on the "Dispute this" link which will ask for some additional contact information.  Fill out the contact information, then in the bottom section select: 

Dispute reason  

  Issue with my Accessories, Supplies and/or Software. 

In the comment section indicate that you have a defective supply that is in warranty, you have verified the supply is defective by switching it with a replacement supply.