You might want to print the ink separation page, and make sure each shade is in the right position. The Eboni-6 from darkest to lightest is K, C, M, LC, LM, Y. Piezography K6 is K, C, LC, M, LM, Y. MIS doesn't list what "shade" each ink is—only what color position it goes is. I mark the position and the shade on top and sides of the bottle and triple check before refilling—especially with the larger cartridges. Luckily those 1400/1430 carts only hold about 15ml of ink so if you did mix it up you aren't throwing too much away. The best bet might be to drain and refill and then see if you still have the problem.
Richard Boutwell