I found 3 pieces of the plastic guides in the back

I found 3 black pieces of the plastic guides in the back which are part of the paper feeding system. They don't seem to be broken. It looks like they just need to be snapped back into place. I'm not sure how to get the unit apart to allow me to try to replace them, or in the event, purchase new pieces and install them.
Is there a diagram of this printer on line which would detail the construction of the printer to allow me to replace them.
Thanks, Jim