A couple hints if you're still considering cleaning your Oly rangefinder: The clear glass surfaces are easily cleaned with a mild lens cleaner after blowing and brushing off as much as you can. BUT - don't clean the angled, colored pieces of glass. Some of the old rangefinders have very delicate coatings on the angled image splitting glass that comes off easily. Also, the cement holding the lenses in place is brittle. Be sure you use a toothpick and cotton to make thin cotton buds to clean into the angles. If you use regular q-tips you can pop the lens loose by pressing into the angles. If you want detailed info I may have some pics I can send you.