Hello I have had my printer ( Mutoh 1641 SR) for about 3 years and lately I have noticed that my black looks green especially if its a large area like a banner with a black background. I'm getting a good nozzle check and have played with the color values. I can get a good black if its a small area like 2 feet or less. I replaced the cap top about a month ago because I have was having issues with Cyan and Black dropping out. The drain tube to the waste ink bottle isn't clogged. What else can it be?