You are dealing with a couple of the big challenges with this light.
I'm guessing the poor lux numbers are due to the emitter no longer being properly focused. It's a big deal because the reflector is designed to project the light out from a fixed point in the base of the reflector. It sounds like you remitter is now lower than it should be and maybe also off center. I'm I reading you right on that?
Be very careful grinding. I tried that on a HD2010 (similar reflector design) and ground through the finish in 2 spots. The reflector is likely thinner walled then you perceive it to be down in that area. I don't know the answer as I have yet to revisit this issue after ruining my HD2010 reflector. Look around the HD2010 threads for a solution as they have about the same problem. Check out what this DBCstm did in Post 461 of the following thread (he has since taken this emitter out and gone to xpg2. Look toward the last post in the same thread.):