The problem is that the pivot is off. It's at 0,0,0 which is slightly off center of the model because it isn't a perfect circle space anymore. which ruins the ability to rotated uniformly around or array. In other words, arraying it will not line it up with the rest of the scene. My biggest question is ... how would you…
You can set the pivot to where ever you like in the hirarchy tab (button next to your modify tab). So probably should be at 0,0,0 assuming you started your project from center. You should get the piece on the left with symmetry or mirror then. And for something like on the right you can use a radial array.