BLF A6 (Astrolux S1) Head O-ring Reassembly?

I accidentally took apart the head of my BLF A6. I can’t seem to figure out how to put it back together. Where is the O-ring supposed to sit?

There are 2 channels in the reflector/heatsink, but if I put the O-ring there, the lens has some play when I screw it all back together.

The reflector also has a small ledge on top, but it’s not big enough to keep the O-ring in place while I screw the head back together.

You need to put o-ring between head and glass lens.