I think the problem is with the printer. The cart seems fine, the printer doesn't complain about the ink level - or anything for that matter. It's only when I go to print that no ink comes out of the LM channel.
I guess I could re-profile the printer and use one of the unused channels instead, but what if that one goes bad next ?
I was hoping that someone could convey a good technique for clearing a blocked channel. The last time I tried to clean the printer myself, I regretted it.