I have a 4 year old Epson R2880 (only light use) using Epson inks which on the whole I'm very happy with. However I do find that occasionally when I try printing in ABW mode I get a colour cast (either magenta or greenish currently). Same paper, all other settings the same, only thing that's changed is I've recently switched back from doing a small print run using the Matt cartridge. I've run a head cleaning and alignment check but no joy. Has anyone any ideas on how I can solve this frustrating problem?