I've been printing for some time with a newish R3000 and K7 inks without any problems. Recently however, I've come across an annoyance.
When I've completed setting up an image and reach the last step, and hit "Print," I get a message that the PK cart is (suddenly) not being recognized and to address the problem. The PK cart, of course, is filled with flush fluid and has never been involved in making a print.
Originally, I would open the cart compartment, remove the PK cart, give it a cursory inspection (no, the chip hasn't fallen out) and reinsert it; the error message then disappears. I've since learned that merely opening and closing the cart compartment without removing the cart does the trick. And merrily, I proceed to print.