When I got lines like it was because of the lead-screw coupler.
I order for this too be what is happening you would have to have a 1.25 - 2mm pitch lead-screw.

Lead screws 3.jpg

From left to right T8-8 4 start lead screw 8mm pitch turned one revolution.
Center is a T8-2 single start lead screw 2mm pitch turned one revolution.
Far Left is a standard 8mm all thread used as a start lead screw 1.25mm pitch turned one revolution.

If you are using something like the two on the right then it could be that the lead-screw is not centered in the coupler.
I have to do this with my couplers wrap a single layer of tape around the lead-screw the press it into the coupler.
This allowed my lead-screw to turn truer, I also had a coupler that was sprung and wobbled this too required replacing with new coupler.

Now my Z-striping no longer exists. Hope this information helps you.