Gaps in top/bottom shell

[Mariner 0]

As picture show i am printing cylindrical objects thats going to be a part of a functional object requiring high radial strength. However my prints almost always missing one wall in about every other layer of the top and bottom shells. I beleave the problem to be in the slicer and was happy to find the "fill gaps between walls" setting but it did not solve the problem. It is clearly visible in the picture in the module of the radius.

What to do?  I loose a lot of strength this way and the part need all streinght possible.