Hey there! Unfortunately I couldn’t find the part but did get a replacement unit. It’s just a small rectangular glass lens with polarized film on it maybe 2x3” if you can find the lens it’s an easy swap to pull it out. One option would be to find a unit for parts and pull it. What happens is the film on the lens heats up and starts to burn causing the brown spotting. The replacement I have is around a year and now slowly doing the same thing so I am searching for a parts unit, the lens, or just an upgraded unit that won’t have this issue.
Overall its a great little projector albeit and little weak on the light power but it does a fine job at night!