Looks like I’ve read more than a few posts where similar Z axis issues were ultimately solved by slowing down, lubricating the threaded rod or a combination of the two. In my case, I found slight binding during the initial motion testing of the Z axis. Ran the axis up and down numerous times to break everything in and it quieted down. Then on my first test cuts I had the issue of the axis not raising correctly in between cuts, resulting in the crazy plunges folks sometimes see. A liberal application of white lithium grease and I have not had an issue over the course of a month and dozens of projects. Perhaps something regarding lubrication could be added to the build guide? Might nip a few problems before they become problems.