BenQ HT2050 shadow / discoloration at the top of the image.
Apologies if this is in the wrong section. Looong time lurker, but I've been trying to figure this one out for a few days and decided to reach out to some of the experts here.
Quick backstory. Our BenQ HT2050 had a really bad dust blob issue and we went back and forth with BenQ trying to RMA it. (For more than a month.) Finally gave up and cleaned it out myself. Of course BenQ finally sends an RMA label a week later, but I never sent the projector to them since I had already cleaned it. All was well up until about a week ago when a handful of spots and a "shadow" started to creep up. (I thought this might have been a hair.) So, I cracked it opened, cleaned it out, and the spots were gone. However, the shadow is still definitely there. Top right of the image. I've attached a picture to this post.
From what I've read, this is PROBABLY a light path issue. Although it looks different enough from the few examples I've seen to make me wonder. The tunnel looks fine (from what I can actually see of it), mirrors look fine, lens looks fine etc. Next step I guess is to take out the tunnel and make sure it's still solid ... but I wanted to hopefully get a few opinions before I do so. I'm more than comfortable working on it if needed. Any ideas?