My HP Z3200 prints suddenly showed a distinct deficiency in red.
A nozzle check print showed no red swatch at all, instead showing a black swatch identical to the adjacent black. Note the left-hand print, above. The swatch at extreme lower right is printed as pure black.
I subsequently pulled the red cart and noticed that it felt empty. I replaced it and, a couple of nozzle cleans later, my red was back, as the right hand print shows.
At no time did the printer inform me that the cart was empty, it simply decided to begin printing black through the red channel.
Comments? Ideas?