MFC8210DW

I have a curious problem with this printer. I received this unit with a jam problem but when I try the fax, the situation that I've find was that the paper was going out blank and the printer always give me an error message for a Tray 1 paper jam, but the paper was not jammed.

I've cleaned all the sensors including the small one over the tray 1. I even dismount this sensor to check if a piece of paper was not stuck in this sensor. Everything is OK on that part.

Does anyone have an idea...

MFC8210DW