If you let the cartridge sit for a day after shaking it, (do not use that first day), any bubbles that were caused will rise to the top and there will be no problem.

It sounds like bad ink because it happened after black spots then a change of black ink. When black ink settles it can change color. I have seen the ink for the 3000 turn green. The 3000 gets the bottom ink last, a cartridge gets the bottom first. If it settled the green would be on the top and the black will look reddish.

Do a nozzle check first. See if every line is there and not broken. Then print out the squares, look around the black square to see if there is any stray black dots from side spit. Special way to clean for that. Different models use a different method of physical cleaning, I am only familiar with the 3000 and the C88.

Sub ink is an ink with particles that can build up at the jets unlike the standard ink. Let us know the results.

Philadelphia, PA (Really Bensalem)

When you finally understand it completely... it changes.