Took it apart today. The assembly inside is very simple, but the free play at the center isn't easy to fix. It's basically due to poor design and/or cheap manufacturing, but it's a cheap stick, so I can't complain considering I intend to replace it before too much longer. It's loose because there is a tiny amount of space in between the bottom of the stick and the hemispherical things it contacts to move the potentiometers, when the stick is in the rest position. I glued in some paper strips try to fill it in, which helped marginally, but in the end it's just a relatively cheap stick and there isn't much you can do. (It's the best of the "cheap" sticks though, IMHO)
I'll probably drop the cash for a the CH set soon, or maybe I'll get the X52 if that turns out to fix some of the downsides of the X45.