DO NOT wipe the lens with alcohol, or q tip or anything else. You could use a micro fiber cloth, but that about it. The anti reflective coating on the inside of the lens is very delicate. If you scratch it, you're gonna hate yourself.
Besides, if any alcohol drips onto the reflector, it's going to leave a spot on the reflector that's going to drive you crazy.
Also DO NOT wipe the reflector with anything. If you do, you will leave marks on it, no matter what you use.
As stated above, the bezel ring does unscrew. From the many that I've opened, some just unscrewed very easily. Others came apart after putting the head in a vice and putting a strap wrench to the ring. Still others needed to be heated with a heat gun on in an oven at 170 to soften the epoxy. You just don't want it to get too hot because the reflector surface will bubble if you do.
Personally, I'd just shoot some air into the head and see what breaks loose, then forget about anything that didn't.