My 7800, using ConeColor inks, has pretty much always had a slight bias towards the red. But I had been printing all day yesterday, and in the late afternoon, I noticed that the red cast had gotten pretty extreme. It is so far from my recently calibrated NEC monitor that all I can do is guess for the first print, and then just keep using small print to guide me to the bigger one. I keep the cartridge shaken, at least once per week if I am not using the machine. The ink is only a month or so old. Any thoughts as to what might be happening.