mutoh valuejet 48in printer not printing right

[vinylink0331]

Hey guys, been a while since Ive been here. Hope everyone is doing well.
I have a problem with my black ink. All other colors appear to be printing fine but the black is printing with lines running horizontally. All other colors have good coverage, look perfect, etc. but the black is very light with the lines. Also, all colors with black in it show traces of the horizontal lines. Any ideas what could be causing this?

 

[vinylink0331]

I think I figured it out. The black ink cartridge didn't warn us when it was low. We had replaced one of the sensors i think. I think it was just running out of ink. We replaced with new cartridge and going to do a good cleaning and see if that fixes it.