You know how you put something away thinking that you'll get it out again soon and use it, and then don't? Well I put my precious Leica rangefinder in my safe several years ago and let it sit. I got it out today in preparation for future airgun use and found a swollen 9 volt battery inside. The battery had leaked a small pool of acid into the bottom of the compartment and ate into the plastic surface. I applied some baking soda water with q-tips to the area, and then used soapy water with q-tips to remove the material. No wiring was affected, but now i have an amoeba-shaped rough spot in the plastic surface at the bottom of my battery compartment. 
I won't be doing that again!
Bob
I won't be doing that again!Bob