Second-hand machine, the previous owner did not attend to keeping tool holder tapers clean, and the ISO30 spindle taper suffered aluminium chip intrusion, gouging, as did the tool holders. The spindle has been reground, balanced, and draw bar adjusted by the manufacturer, with a reported result of 1-2 microns of runout- however, a deep, sub-surface gouge all the way around the tapper could not be removed. They reckon it should not impact performance- what say you? Are there implications for the tool holder tapers?