Slicing like that can’t work since you have curved sections mixed in with the straight sections. You need to move the slices closer together, so the curves are isolated in their own sections. Also the image would benefit from extending the middle section vertically a bit, to give the slicing something to work with. As it is, the horizontal slices would have to be nearly touching, and it’s hard to tell if it would quite work. On the other hand, the horizontal straight section is needlessly extended and could be mostly eliminated; you only need a couple of pixels.