Anyone have any experience cleaning the inside of a watameter I? I found one for about as cheap as I'm going to find on fleabay, and it's in ok shape but I see a little grime on the inner mirror. I can use it without cleaning, but it's too nice looking on the outside to leave it this way. I'm assuming the two screws on the front take the front cover off. If I leave it face up, should everything stay put so I can clean with a cotton swab? *edit* Ok after now reading up on rangefinders (first one I've owned), I'm not supposed to touch the half-silvered mirror with ANYTHING, is this correct? What about the yellow plastic?