I was going to rant. I was going to rave. I was going to find a voodoo doll of my printer -- or maybe of Photoshop -- and stick pins in it. Because after I had spent a decent amount of time cleaning up a scan and getting it just so on the monitor, when I came to commit to print, the blasted image had horrible green splodges where there should have been deep purple.
Printing really is the last area of computing that does seem to require the sacrifice of a black rooster while turning widdershins three times and whistling "Satan is my Lord" backwards. I know enough to know that the print will never look exactly like the monitor. But I do think it should look reasonably similar. And having committed to a continuous ink system (so that when I am wasting paper and ink at least I don't have to worry about running out of exorbitantly expensive pigment) and to a single paper, and endless tweaks to get a pretty good match, this was almost more than I could stand. A bunch of money down the tubes, it seemed.
So I slept on it, and the next day I tried again. Same image, different paper, different profile. Even more green. Even more anger. I'd read in a couple of places that an overall greenish cast to an image suggests that both software and printer are trying to manage the colour, but I checked and double checked and that was not the case. Then something clicked. What else could cause purple to turn green? How about a straightforward lack of purple pigment? So I took a look at the ink reservoirs, and they were all fine. (I should think so too, after only half a dozen prints from the new system.)
And so, finally, I came to do the obvious nozzle check. Bingo! A total absence of magenta. Four cleaning cycles later, a perfect print.
p.s. 21 September 2017: I continued to wrestle with the printer and its benighted continuous feed stuff and nonsense for a good long while after this post. Eventually I gave it up as a bad job and wrote off the whole sorry experience. Professionals do a far better job than I could ever manage.