Pegleg, you're welcome. Hopefully you are near this bass and can check it out in person? I think that's the important thing. Stock, the Spoiler should have just two pickups, the filter, Q switch, and a volume control. Who knows what the mod may have done, as Dave says. I am not sure if the circuit board of this vintage would be printed, or hard-wired perf board. At any rate, it should not look sloppy at all.
So to add a third pickup, someone would have had to tie the signal in somewhere. He may have run each pickup to one silver toggle switch (Alembic used black, btw) and from there into what used to be one pickup input for the filter board. Note that all three silver toggles are part of the mod.
It's a huge unknown and without really checking the bass out, opening the control cover, and looking, you won't be certain.
If this is the bass in the picture I posted, bear in mind the price is not at a huge discount considering the mods. A stock Spoiler is sometimes about this price.
Of course, if the mods were done at the factory (only they can confirm) then it would be highly unusual but that would rule out a sloppy amateur mod!
Investigate more, and post what you see or hear.
EffClef
