Casio CZ/ VZ/ FZ - Pro Series

Maxim wrote:  

"The synths is in fine shape, but in the past months the
battery seems to be getting low, so you might want to change that
(since I only used presets, this didn't bother me too much,
but I suspect somebody will want to actually program it)."

I have the V8M operation manual, and it doesn't seem to say how one
would go about replacing the battery (though the specifications do
mention that the battery life is 5 years).  Does anyone know how this is
done and how easy it is to get a replacement?

-- Jeremy