MAYBE...the paper tray just isn't fully seated and/or that clip is part of the tray(or tray area) that causes a sensor to be defeated(allow use) and/or allow a snug/proper aligned fit. This is a part that unless returned may cure you're problem. Unfortunately, I can't recall such an item. It just isn't good to find parts lying about.
Many times when no true fault can be found, then either a sensor, paper chad, or broken mechanism is at fault. However, only a tear down is best to locate such and get a picture of what should be. Detailed schematics help here and if a frequent problem(s) reported by co. tech notes.
I found a little metal clip, that maybe goes in the paper tray somewhere? I took a couple of pictures of it.
Anybody know if this is even from my printer?