Best posts made by Cadu

@dc42 Tyvm for the response. I will do that with a scope this week. A subsequent bed probe with the second effector had a single point with similar error and coordinates, so I did a full teardown and found a likely contributor. The Seemecnc Rostock MAX series use two idlers at the base and the inner idler is hidden. Previously I had inspected the belts, motor pulley, and bottom idler but not the inner one. The combination of hairspray on a glass bed(with a sheet of paper covering the base of the belts but not the entire tower so some mist would float up) over a couple years had captured small particles of belt compound and filament dust and formed a couple beads the consistency of rubber cement between the smooth side of the belt and inner idler. Depending on speed and coordinate travel, this bead would change shape from a smooth, <0.2mm ellipse smooshed against the idler that didn't show errors to a 1-2mm hemisphere bead that would. Each of the 3 tower inner idlers had this bead, in different shapes, and removing them reduced(but not eliminated) the bed probing errors. This sticky bead was sequestering common signs of wear so the other sections looked pristine.