To prevent fungus growing, always store the F2 in a sealed bag with a moisture absorbing packet inside. I use two sealable sandwich bags per camera, and that's worked well. Also, to avoid condensation forming inside the F2, always put it in a sealed bag before taking it from a cold place into a warm and humid place.
When you buy/bought an used F2, always smell and check carefully for signs of fungus, or rust/corrosion. Avoid buying F2s from humid countries/states, as it's almost certain that they have fungus inside. Send the camera back and demand a refund if you find any signs of fungus in the camera. Chances are if you see some fungus on the outside, there are a lot more fungus inside.
