Hello guys! This month I brought in another Mimaki tech. He changed the captop and seems problem is really the printhead.
Nozzles are not clogged, because he pressed the damper before printing a test and a lot of magenta dripped on the media when the carriage moved, but nozzles wouldn't fire at all. He disconected and cleaned the contacts in the electric cable of the head, but nothing changed. Also, he noticed magenta ink is mixing in the edges of cyan line and that's why he didn't even inverted the dampers: according to him, this mixing means that probably the internal chamber of the head is breaking and simply removing the dampers could break it all at once and I could not print anymore.
I asked him to do what you recommended
Boyanski , he agreed at first but didn't do it because of that internal chamber issue with mixing colors that he detected after changing captop.
And a few days ago, I also lost that cyan line that was mixed with magenta (it was ok in the morning and in the afternoon, boom, no cyan!). Now black is beginning to mix with yellow, which makes me think that yellow will disappear soon. Back in december, I thought this mixing was due to a bad captop, but apparently it's something worse. This printhead is not even 2 years old and has less that 1 billion shots per line, can't believe this is happening
Dollar rate is high in my country, economy is bad and even if I manage to buy a new printhead, warranty is only 3 months and I'll be even more broken if I buy it and it starts to fail again in a year or two. I can't believe those printheads are disposable!