for what it’s worth, I decided against NVRAM on my WPC games. Mainly because TZ actually does use the clock function and possibly effecting the song lineup in my CFTBL. My solution was the coin cell board No Quarters makes. Way easier to do (just desolder the battery holder) and the batteries will never leak and last for many years. And keep my TZ & CFTBL as they should be.
Just a thought.