I am so new that I have never replaced an ink cartridge.  Print was wrong color, banding etc...  I did test print and 85% of the magenta is dropped out.  Removed the cartridge and they feel awfully light but printer doesn't say it's empty.  Tried a head cleaning and only the exact same lines fire. I will order some ink tomorrow but I would like an education.  Also this printer has 6 colors 12 cartridges.  Will it still print if only one cartridge is full or is it mandatory to have ink in both?  I would like to run the machine on 1 440ml for a couple of weeks and then replace the other so that both cartridges won't run out at exactly the same time.