2 of the 4 colors (red and black) are not working on my HP Officejet Pro 6970

[gensurf]

I just put 4 new cartridge in my printer and noticed only blue and yellow were printing. I put the old red and black cartridges back in (low but not depleted, as diagnosed by the printer) and attempted to print black only. Got a completely blank sheet. Do red and black colors are not printing at all. Cleaned the printheads to 3rd level. Printer maintenance conducted by the printer shows no issues.

[Kumar0307]

@gensurf, Welcome to the HP Support Community! I’m here to help.

I understand the printer is printing blank pages. Make sure you are using HP ink cartridges. I appreciate your efforts in trying to resolve this issue by performing the necessary troubleshooting steps.

Make sure you have tried the steps mentioned in this document - Black or Color Ink Not Printing, Other Print Quality Issues

Check the ink level on the printer screen and replace any low/empty ink cartridges.

Clean the printhead up to 2 times and print a test page to check the result.

Try making a standalone copy from the flatbed glass and check if that works. By this, we can conclude if this is a hardware or a driver issue.

If the issue persists even after replacing the ink cartridges, I'm afraid this is a hardware issue with the printhead and it is non-removable on this model printer. 

If the printer is out of warranty, I suggest you upgrade the printer. You may visit Hp Store to check the available printers.

If the printer is working fine with alternate Magenta and Black ink cartridges, it could be the cartridges that are defective. In this case, please reach out to the HP Technical Support team in your region regarding the replacement options. 

You may create a case on the website to obtain a case number if required. Kindly watch this video to know how.

Keep me posted for any other assistance.

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Have a great day!