Hi all, those of you who have read some of my previous posts may know that collecting Pentax cameras and lenses is an interest (i.e. scary obsession) of mine. Well, I spotted a 50mm f1.7 lens (PK mount) on Ebay and immediately went for it. Of course buying on Ebay is a bit like sticking your arm in a barrel full of snakes in search of gold at the bottom (weird analogy I know) and this time I got bit. The lens arrived and the seller left me good feedback, however the lens appears to have a significant amount of fungus on the inside of the elements. Since the lens cost me £10 including delivery I won't bother arguing with the seller, however I am prepared to try taking the lens apart in order to clean it. Unfortunately it doesn't seem to be that simple; the mounting ring on the back of the lens is screwed on but the screws will not budge (I've chewed up two screwdrivers trying) so I can't seem to get inside the thing. Essentially what I'm wondering is whether anyone knows anything specific about cleaning lenses of this mount, or whether (a long shot here) there's some kind of miracle cure for cleaning fungus from inside lenses without disassembling them? Thanks in advance for any advice you can give!