DIAGNOSIS Not a dud. The printhead nozzles are almost certainly clogged. EcoTanks sit still a lot, and the pigment in that ink can dry in the tiny nozzles if you don't print weekly.
FIX You need to run the head cleaning utility. 1) On the printer's control panel, press the Home button. 2) Navigate to Setup -> Maintenance -> Print Head Cleaning. 3) Follow the prompts. This will pump fresh ink through the nozzles to clear them. Run it once, then print a nozzle check pattern (also under Maintenance). If it's still bad, run the cleaning cycle one more time. Wait a few minutes between cycles.
IF THAT DIDN'T WORK For stubborn clogs, use the 'Power Cleaning' option in the same Maintenance menu. This uses more ink but applies more pressure. If streaks persist on one color, that specific channel might have an air bubble. Print several full-page color graphics to push ink through.
HEADS UP These cleaning cycles waste a noticeable amount of ink from those tanks. It's normal, but it's why you should try to print a color page at least once a week to keep everything flowing.