When you look at the bass again make sure the neck is straight. As far as I know none of the early Modulus basses had truss rods so you won't be able to make any adjustments. If the string tree is not stock it may have been put on because of issues with the neck. Regardless check every note on the neck to see if there are any high/low frets, warps etc. If you have to pay for a fret job in addition to the electronics the cost for this bass is going to start to approach getting a newer used Modulus (though maybe not in France).
Good luck, hope ithe bass works out for you!
Good luck, hope ithe bass works out for you!