Having these build quality issues with the Hejnar Macro Focusing Rail MS5P-10-KS of USD, I am not happy, especially Hejnar told me they have nothing to do with the poor lead screw because the lead screw provider only can offer such quality. I totally don’t believe this. Even the screw material has defects, Hejnar can cut a perfect section from it as the part of the macro focusing rail. But I suggest that the best and quick way is changing the screw provider, and China made stainless steel screws seem to have much better build quality and are cheaper. I don’t recommend Hejnar’s any macro focusing products equipped with lead screws unless they have a big improvement on the build quality and can guarantee that the lead screw, the core mechanical part, has enough precision without any broken sections.