3 printers, 2 6152s 1 8160. Paper jams in optional trays. Codes are usually 240.xx. For example, if paper feeds from tray 4 then paper gets caught in pass thru ( pinch rollers ) of tray 3. Caught in these rollers. If paper feeds from tray 3 paper is caught and crunched up in tray2 pinch pass thru rollers. I see a pattern but can't put my finger on it. Is this common ? Am I missing something simple. Somewhat puzzled here.