I recently purchased a Nikon F3 from KEH EX rating, the meter at first worked perfectly fine. After the first exposure to the cold the meter went haywire (around 32 degrees) and the numbers came up all choppy and the plus and minus sign for over and under exposure appeared at random intervals, ever since the camera has totally warmed up and the batteries even replaced to be sure, the error has no subsided and remains fully in effect, whats wrong with my camera?