Quote Originally Posted by wiltw View Post
Spotmatics (original, II, F) all used mercury oxide batteries, and given the stable voltage from those batteries it would be surprising that a bridge circuit would have been used. Nevertheless, the Olympus OM-1 is absolutely dependent upon constant 1.3v, its meter does not align two needle but is similar in appearance to the Spotmatic (align needle to center of indicator area), its needle swings out when power is off.
Surprising or not, it's a fact. I have six of them, all rehabbed by myself. I'm quite sure of it.

As someone else said... trying to force the battery cover off is a good way to screw it up. Take off the bottom plate and soak the whole shebang... try a light vinegar solution first, that will usually do the trick without anything toxic. If the simple soak doesn't do it, use a sharp blade to pop off the hump that covers the battery on the inside of the cover, and try the soak again. The hump is easy to re-affix. From there, if still no luck, move on to stronger solvents. But I've never needed it, and I've worked on some that were really burned and frozen.