I attached the photo you sent below. Based on this print, it looks like your black isn’t printing.
Since you said the exit chambers were pretty empty in several of your carts, I suspect you ran a few carts empty and may have some air in the lines.
Two things to do: 1. Please check to make sure the air vent holes are OPEN on all refill carts for proper ink flow, and 2. do 1-2 cleaning cycles, then print a nozzle check to see how the positions are printing (a good nozzle check should print eight ink channels).
Please let me know if you have questions, your results, or if there’s anything else I can help you with.
Best regards~ Dana