Casio CZ/ VZ/ FZ - Pro Series

Okay guys,

My cartridge doesn't save names on the patches and only retains the 
patches that I do save for a few minutes.  Then poof-gone!  Thankfully 
the batteries inside my cz-1 still work.

I've read from past posts that this means that the battery needs 
replacing.

I've read one place that the RA-6 cartridge have a AAA battery inside 
that needs to be replaced and I've read in other places that it takes a 
lithium battery I can pick up at radio shack.

So:
1.  What type of battery does it take?
2.  How do I replace it?  How do I open up my cartridge?  Do I need to 
know how to solder?

thanks
mjb