So I have a Roland SC-540. its about 5-6 years old. The black Keeps dropping out. Its not the head, because i have switched the black to the magenta, then back to the cyan etc - the cyan and magenta work fine on that same head. But the black, it prints ok for a few inches then drops out and just prints lines and the head blocks, but its not actually blocked, I push cleaner through the head and all jets fire fine. So I have changed dampers, several times, switched heads, I have flushed the tubes with cleaner, pushed in the cartridges to a tighter fit, if thats possible. Still keeps happening, has this happened to anyone else? Im pulling my hair out trying to fix it, Ive bought some new cartridges (dont have them yet) hopefully that helps, but i just switched them up for some that i already had that and still doing it. ANY Suggestions please, In desperate need of help! Wasting too much time and money trying to fix this pain of a problem.