I won one of these lenses from eBay for the princely sum of $15 shipped... For that price I was expecting fungus, or terrible wear and tear, or both. Turns out it's in great condition, except from the fungus part. there's some in an inner element, so I decided to try and take it apart. I can get into the lens by either end, but can't seem to find a way to the aperture or the elements around it. I can't see screws or other means of getting all the way in there. Anyone attempted it with this lens (of similar)?