I've got that exact same lens. I had some fogging between those two elements on mine, and I ran into the same road block you did when I tried to separate them. What I eventually did was dipped a Q-Tip in some solvent and ran that around the edge and let it soak in between the grooves, then it popped right out. It appears the front element is glued down. I can't remember which solvent I used, but it was probably rubbing alcohol or naphtha.