I just bought a working Olympus om-2 for about 13 bucks with a pristine 1.4 50mm. Aside from some green spots on the exterior it's in pretty good shape, but there's some fungus beginning to creep up two edges of the penta prism towards the bottom of the viewfinder. Looks like a little forest sticking up! It's very usable right now, but I want to make sure it stays usable for the foreseeable. Is there anything I can do to slow down or stop the growth of this fungus?