Digital BW, The Print

Hi,
since I�m now succsessfully printing with my epson r285 (Germany) and Ultratone 3d in it for some weeks, something makes me nervous. Nearly everytime I print out a noozle check pattern I see clogs in the MK-position (I leave it in all the time cause I figured out (with the kind help of Paul) how to print on glossy and Matte with the dark greys building black for glossy). So even after one or two days the black position does not ive a proper noozle check. Is that normal? Any ideas how i can avoid this?

Marcus