I have bought a couple of legacy lenses on ebay. From the pictures and descriptions, these lenses do show some dirt and dust on the lens casing, and one of them supposedly has a little fungus on the front-lens element (sample pictures from the lens looked good, so I went ahead and bought it). Are there any tips for cleaning the lens and casing, and also on possibly cleaning the fungus? I've read some people recommend rubbing alcohol, while some say don't use it. Others recommend Hydrogen Peroxide or lens cleaning solution. Please advice. Thanks!