Unexplained loss of sound/response

[Ken Smith]

You might need a new longer sound post. Overtime, the back can swell outwards from the sound post pushing on it. Wood does move and maple is a good bending wood. Also, the top gets pushed out from either a tight fit or/and an ill-fit post. Some of the Luthiers over here my way (the ones I work with), are very particular about how a post has to fit. One of them actually said once that a neck graft is easier than fitting a post. Probably because you are working half blind with lights and mirrors while cutting and fitting a Post.

Now, as far as what your bass is, who knows how these Chinese basses break in over time. So, unless someone on the Forum pays you a personal visit, it is all guessing here.

Look down the Back and see if it bulges differently over the Post area more than the other side. Also, look at and feel the Top under the bridge foot and see if you feel a 'lump' from the post pushing on the top. If you can get a light and mirror, look inside at the top and see if there are any dents on the wood. If so, that's from the Post Not being fit flush with the top. As one moves the post, the fit is different. The top can be cracked as well from an overly tight post.