Hello, not too sure this will help but I would manually try using a manila folder and feed it through the paper path from tray 2, my guess is there might be a sensor out of place or something. So remove tray 2, the toner cartridge, and try that. Chances are it may adjust the senor or you can determine if something pushes a possible piece of torn paper out. Again, not sure if this will do the trick since you mentioned taking apart the machine.
Hope this helps.....