having a problem with several heads miss picking 8mm feeder parts. Had to bypass 2 of the heads because it was becoming such a hardship. Heads 3, 4 (bypassed), and 8 (bypassed). On 3 and 8, it will miss so many it errors, and when I clear the error, with doing nothing else, it starts picking properly. Head 4 just won't pick anything. Filters appear clean, and nozzles are clear. On the error report, 4 and 8 lead the way with the largest pick error pct. I'm a newbie on this machine so I am OJT. Any suggestions?