weire truss

[dooft11]

Dear all
i own a bass by an unidentified luither brought from ebay, the wood is beautiful, almost all maple. which should be a slapper heaven, however, it is not, the slap sound a bit hollow, will it be due to the neck thu construction? the Bart pre? or wrong wood combination? may be i should post some pic of it

On the other hand
the truss rod has some weire layout. the bass has two truss rod, and the wet weather in far east make the neck more towards a backward bow(less relief between board and string) which i suppose to loosen the truss to bring more relief. however, i found that the one on the G string side was total loosen which i can only tighten it, which is weire, the one close to the low B is working as normal


so i will guess it was a broken truss.. or do you had seen some special layout at that? any good way to ease the situation?, i am thinking of heavier gauge(but it reduce my playability some how) or turn it to a 6 with more up tension... anything you can think of?

Thanks.