1. I have a Sirefire 618FA and have always run the SF xenon bulbs, but finally bought a Malkoff M61 for it. I dropped it in; however, it doesn't work. I've read a couple different things, but to no avail. Some people suggested pulling out the black piece on top of where the batteries are, while orhers have suggested buying a ring? Is it a special magical ring, or will an appropriately sized o-ring from HD work? Does it go in front of the unit around the bezel? Any insight would be appreciated.

2. My other question is in regards to my Pentagonlight MD2 led. It already has an LED; however, it doesn't have much of a throw. Any known upgrades for these?

Thanks gents!