Sounds like a lot of monkeying around under the hood.
Pickups should have been EMGs to start with, and the toggle(s) are likely unoriginal. Hamer's wiring is extremely neat/tidy, and minimalist, so even without a control cavity pic, my guess is that not much of anything in there was in there when that bass left Arlington Heights.
Awesome bass - I still want one of those, despite the spine-bending weight they all have.