Not sure what's wrong with my '84 Spoiler. The sound is there, then starts fading, then gone, sometimes comes back, then gone. The battery is new, the cables and amp are okay. Any ideas? . . .

When you say the cables and amp are ok, I assume you mean you've checked them with another bass.  And when you say the battery is new, I assume you mean you've tried two new batteries and both give the same results.  Perhaps it is a leaking capacitor.  See the following threads:
 
http://club.alembicguitars.net/Images/394/6101.html
http://club.alembicguitars.net/Images/393/5565.html?1059952279
http://club.alembicguitars.net/Images/393/5788.html?1061764625

Does it sound the same in both pickups? If so, it's very likely not to be the pickups. I suppose you could swap out the 14-pin TLE2024 IC on the preamp board. It's socketed, so you don't need to solder, but it's usually easy to get acces to it and make sure pin 1 is lined up properly if you remove the electronics.

Back in business! Pretty sure it was the battery. Thanks Mica and Dave, you guys are awesome.