BigAl

I have a JV Precision hanging on my wall with a broken truss as well!
I got it like that cheap and don't really need it so haven't done anything to fix it.

I would suggest that if the truss doesn't seem to be straightening the neck out enough that it has bottomed out.
Anyone else having this problem should check the http://basschat.co.uk/topic/97682-truss-rod-maxxd-out/page__view__getnewpost thread.

The batteries ran out in my Big Al months ago and despite having spares I've felt no need to change them.
It still has the big full sound I like in passive mode, with plenty of the bite you would expect from a Musicman.
And that's with really dead strings too...