Had a CS 2560 that had a message on the operation panel that said ‘add paper in tray 1’. I could not get past this message. I could not feed from tray 2 or MP tray (could not select either tray). Swapped feed sections and cassettes from tray 1 to tray 2, but still same problem. Reseated all connectors on the engine board. Tried to do a U906, but would not allow me to do so. I could not get past this message. After talking to tech services, I disconnected fax card and everything worked fine. Put fax card back in and was able to use all functions. Faxes also printed out from memory. Was even able to do a U906. Fax still worked and everything on machine tested fine. Hope this helps someone else with strange problems.