HP Designjet 30 C7790D Printing Result Overly green/blue - Indication of...?

I'm considering purchasing a used HP Designjet 30 C7790D printer. The reseller said it was acquired from an old print shop, disconnected from the computer, and sat around. That when they acquired it, they got it to print, but the image was overly green/blue. I tried to get help from HP, but surprisingly, they didn't support it due to it being old (I remember as little as 4-5 years ago, they happily supported their older products). So my question is: does the image quality indicate the need for ink and nozzle cleaning, and perhaps color calibration, or is it an indication of a more serious problem such as ruined printheads? The pictures show all of the ink cartridges as full. If ruined printheads, my next question: are the printheads included on the ink cartridge, or is it a separate unit? If a separate unit, is it a swappable cartridge or an entire device that would be pretty expensive to replace? Finally, judging by the description of the issue and the printers age, is it worthwhile to consider this or just wait and spend the money on something more current? Thanks!