In the last week my HPZ3200 has suddenly stopped printing black (MK, on matte substrate) on prints that extend past 24" length. By that, I mean that MK black is laid down at the beginning of the print, but trails off at about the 20-24" point of length. This has occurred consistently across the last 5 prints (ea 24x36"). In attempts to alleviate the problem, I have 1.) rebooted printer and computer; 2.) uninstalled/reinstalled HP raster driver; 3.) reseated and aligned MK printhead and ink cart; 4.) tried different print files (each, however, was at least 34" in length, with the black trailing off each time). Can any HPZ users on LuLa provide me with other troubleshooting tips? Thanks!