The black printhead problem started from a head strike about five years ago on banner material. Has printed fine since, but I always print in HQ mode. I've never changed the captops, it never showed symptoms of needing to. Have always done a manual cleaning at least once a week. Have replaced the wipers, t sponge, misting sponge etc.. a few times. The black ink was one of the first things I checked and it was getting low so I put a new one in before all this testing started. Has only ever had Roland ink in it. I will try the swab on the head Monday if the weekend head soak doesn't help.
Seems to print OK as long as there's no grey in the file.
Since greys are a mix of colors...if the black isn't putting out enough could that cause the grey to be brownish?
I would say that black head is showing you.
Cap tops seal the head. They are meant to be changed every 6 months with a Roland...