I just took an A501 out of one of my Miggies and peered inside by prying open the one unsoldered corner as much as I dared. What I see in there is a fairly furry battery that needs to be taken out right about yesterday! I concur with Oldsmobile_Mike, you really should crack yours open.
EDIT: This little weasel went pop!


Ew. Not a moment too soon.
Also, I spent a good fifteen minutes looking for my soldering iron which I didn't find - I found
another one instead, a
new one in an unopened box, bought a decade or so ago. I'm a
terrible housekeeper...