I recently bought a second hand Minolta Maxxum 7D. It was suffering all the problems I have read about in the various forums inc. shutter failure and inability to turn off thus eating batteries. It is now fine! I took off the back and found the main switch consisting of four slender tongues crumpled over and unable to perform as they should. It was a delicate job to reform them at the correct angle necessitating good watchmaking gear. The shutter problem meant trying everything until I applied 6 volt external power. The camera would not even turn on properly! From that I deduce that there was a battery voltage problem. Having fully charged them and cleaned the contacts....bingo all is well!