MD-12s have problems with short-citcuits in the switches. Mine, which
otherwise is new condition, also has a short. However, the short in mine
causes the power-off timer to either work or not. When the power-off
timer fails the MD-12 acts like an MD-11 and will drain my camera's
batteries.
I'm afraid nothing other than putting it in for servicing will solve the
problem.
When yours goes out of control you might try moving the manual advance
lever to the stand-off position. While this won't solve the problem, it
will allow you to stop the undesired exposures a little quicker than
trying to get to the small black power switch of the MD-12. Once you've
moved the lever to the stand-off position, you'll need to shut off the
MD-12 as usual.
Clifton Painter
