Patches and discussion for Ensoniq VFX family

I have a VFX that has been fully upgraded to a fully expanded SD-1 
with 75K note sequencer. If I don't use it for several days, the 
sequencer needs to be reloaded. I am sure this is a battery that is 
nearly dead, since I have owned this thing for over 11 years. Does 
anyone know the best place to get a battery? I don't mind going to 
the Route 66 folks if they are the best choice but if I can buy 
locally that may be easier. Does anyone know the replacement number 
on the battery? If I get this info, I can search locally. I am 
comfortable with taking the instrument apart and can solder extremely 
well. Thanks in advance for any and all help offered.
Greg