Well, I just burned the coating off of this part! It's a little light tunnel that is mounted in front of the lamp. It must channel the light into a nice tight 16:9 beam into the mirrors before hitting the DLP chip.
I removed the UV filter from the lamp assembly in hopes to prepare the projector for 3d printing and I guess the heat from the lamp just burned off the mirror coating on all 4 sides.
Attached is a picture of the part. I need to find a new one. Anyone know where to get these type of parts? I think the rest of the projector is ok, looks like the damage is just to this little "light tunnel"