Had to do this on a build I had in, go slowly and carefully with the dremel! I made a groove almost through & then used a wide screwdriver to gently crack the bonder so i didnt end up going right through. The projectors on the one I was doing had been disassembled, the blind had been turned the other way up and reassembled. So the light pattern ended up pointing into the traffic and into the sky & the road was blanked off! Someone didnt pay attention in physics at school when they were teaching how light patterns behave!
You should be able to just put a fixed projector unit in as the extreme headlight has those long screws and balljoints for adjusting both main and dip at the same time.
Long shot, but does the light unit steam up? Maybe try having a look inside the projector with the bulb out, the lense at the end may be dirty on the inside reducing light output?