I bought a Vivitar 215 flash and discovered it has corrosion on the battery cover and I can't get it to work. I've sprayed deoxydent on it and soaked it in vinegar to no avail. I'm having a similar issue with my Folks old Konica. Do I need a wire brush or something to get this stuff off? Do i need to soak it in deoxydent for a while? Also, I noticed that AA batteries are often 1.2v when this thing wants AA with 1.5v .I did find 1.5 v but it still didn't work. thoughts? thanks!