Be extremely careful if you attempt to unscrew the large black ring on the G2 model. I unscrewed mine tonight and didn't notice until too late that the entire assembly came out in one piece, twisting the diode leads and breaking the wires off. If you attempt to unscrew the large ring, use a depth gauge or even just a piece of wire to check whether or not the entire assembly is rising before you get past 1/2 turn or so. Otherwise you may be cursing your curiosity as I am right now.