That's a good tip to know. I had an olde folder recently w/ the same type of fungus as yours (not the deep, spidery, etched kind), and like you, I figured what the heck, let's see how difficult it is to get it off. Well, it all came off w/ just some lens cleaning fluid and tissue! Took a little pressure, and more than a few Q-tips and tissues, but everything looks nice and clean in there now. I've also used lighter fluid in the past to get fungus off. If it gets between cemented elements, that's beyond my skills and tools.