As others have said look for a scratch under the head if it looks good could just be clogged. Your black head could be cleaned up and may recover some of those missing nozzles not sure since it been clogged for so long.
Here is what I would do if there is no scratch.
Do this to the black head as well may help recover the missing nozzles.
I have a JV3 and use triangle ink as well.
what I do when missing nozzles is remove the dampner and get a syringe full of flush move the carriage over and fold up a
paper towel and set in on the wipper rails now push the carriage over until the head you are going to clean is over the
paper towel now take the syring with a piece of tubing that fits the nipple the dampner goeas on (its the same size as the pump lines) put the tube on the nipple and push the flush through the head. I look under the head while doing this and apply enough pressure to get a stream (just enough pressure to get a stream) coming from the nozzles Iwill do this for at least 1 but usually 2 or 3 syringe fulls (I use a 3cc syringe I think its 3 cc) pull the
paper towel out and replace after every syringe.
Put dampner back on and do ink fill.
This usually will clear up most of the nozzles if you do it as soon as the nozzles become clogged.
This works for me but I take no responsibility for any damage you cause.
on really bad heads I do the same thing but with an electric pump and I run the pump for 10 min or more with the head removed from the printer (with the pump setup you can see when the nozzles become unclogged and if they dont clear up after 3 or 4 10 min cycles they usually wont clear up). I had a head that looked worse than your black head and built this pump system and cleaned it and recovered the head to only 3 missing nozzles and have saved myself at least 3 heads since I built it.
Good luck
and if you do the syringe thing remember only enough pressure to get a steady stream coming from the nozzles.
On a side note Artbot is the man when it comes to the Mimaki printers I cant thank him enough for the help I have gotten from him. Thank You Artbot.
Final note:
I AM NOT RESPONSIBLE FOR ANY DAMAGE YOU MAY CAUSE USING THE METHOD I HAVE WRITTEN.