Acetic acid, which is twenty times as powerful as white (hops) vinegar can, indeed, be used, but I should have said that one should first impregnate a bit of clean tissue, or a Q-tip, with it and NOT apply it directly to the battery contacts. I have yet to have problems with this method. Sometimes the vinegar is simply not strong enough.

But, other recommendations are also good, even the one using a pencil eraser. And, as far as getting 'bits of steel wool' into the meter: one assumes that all the debris will be wisked away with a small brush before those gremlins get a change to get inside. - David Lyga