HP OfficeJet Pro 6978 is not printing/copying the correct colors from the original document. Cleaned Printhead 3 times. Performed alignment, but when alignment page put on the scanner, it says that it cannot read the document - so the alignment could not be completed. Always use genuine HP cartridges. At first it seemed the Cyan cartridge not working, but replaced it with a brand new one and no change. Sometimes green comes out yellow and blue comes out pink. When we print a black page it comes out black, but when a black page is scanned it comes out red. Printer only 1 1/2 yrs old!
Make sure the ink cartridges are properly vented and seated correctly
Turn on the printer, if it is not already turned on.
Open the ink cartridge access door.
The carriage moves to the center of the printer.
Wait until the carriage stops moving before you continue.
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.
Examine the vent area above the HP logo on the top of the ink cartridge.
If the ink cartridge still has the orange pull-tab attached, pull to remove it.
If the vent is clogged, use a straight pin to gently remove excess adhesive from the vent.
With a straight pin, gently remove excess adhesive from the vent
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.
Slide the ink cartridge into its slot, and then gently press the ink cartridge down until it snaps into place.
Repeat these steps to inspect the vents on each of the ink cartridges.
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.
Close the ink cartridge access door.
Try to print.
You can refer this HP document for more assistance:- Click here
I hope that helps.
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