If I read you correctly, the nut overhangs the side of the neck slightly.
If that's correct, I would try to tap it free with a hammer, by hitting the end of the nut longways so that it travels in its slot, i.e. hit it as though the nut was a nail. Like this: [url="http://www.manchesterguitartech.co.uk/images/refret/3-tap-out-the-nut-4.jpg"]http://www.mancheste...t-the-nut-4.jpg[/url]
I wouldn't do it if you're at all uncomfortable with it, though. If you're not used to using a hammer, I'd pay a guitar tech or luthier to do it.
I would:
- take the strings off the tuners.
- clamp or hold the bass so that you can get at the overhanging side of the neck easily. Be sure not to damage the bass with the clamps!
- Hold a piece of scrap wood or hardboard over the overhanging end of the nut so that you can tap the scrap wood, so that the hammer doesn't hurt the wood of the neck.
- [u]Carefully[/u]! [u]Gently[/u]! tap the scrap wood with the hammer. With any luck it will free the nut in its slot. (If you're really lucky it will just move sideways along the slot a little bit and wind up in the right place )
Disclaimer: I am not a luthier or professional instrument repairer!