I've had my Leica MP for a little over a year. Lately, the battery doesn't seem to be working to use the light meter. I first noticed it about a month ago when a light seemed to indicate I needed a new battery to use the light meter which seemed odd because i didn't think it was so long ago that I put a new one in. Nevertheless I replaced it with a new battery and about a week or so later, the light meter would not turn on when it was supposed to. I took the battery out, wiped it off and put it back in. It seemed to work for about a minute but then stopped again. Anyone know what the issue is?