My SF8AX bezel has become loose, and tends to turn unintentionally. I have put some lube on the threads, with no change. The looseness is annoyingly noticeable.
What about Silicone Grease, it tends to dampen the moving part at least on my E2e bezel as well as it's tailcap. Sort of sluggish feel with lots of viscosity.
Contact SureFire customer services. If you e-mail them they take a few days to reply anyway, so you may solve the problem while your waiting. If not, i'm sure they will be able to sort you out.
All you need to fix that is go to a plumbing store and get another O-Ring. Same inside diameter but slightly thicker. Check here to read about the same situation on a 10X: