we have a C20 and it seems to be only jamming when you print/copy from the 3rd tray. You will get transfer jams, horizontal jams and exit jams and misfeeds randomly every 5-15 pages when printing from tray 3. Have updated pp firmware to current. Controller and engine are current ver, changed tray 3 whole Feed unit with motors and sensors and board from different tray. No change. But when printing from tray 2 no problems at all.