I have a Grizzly G4003G gunsmith lathe which I bought in 2010. It had a lot of great features and tooling for the price. I like it in every way except I have had one problem from the start. It leaves a "harmonic" pattern on any turned surface. It does not seem to be related to feed rate because it happens no matter what feed I choose and also when I hand feed. I have assumed it is in the headstock bearings. I have played with the pre-load on the bearings but this hasn't helped. It is a geared head and I wondered if this could play some role in the problem. Has anyone experienced this with other geared head Chinese lathes? If so, were you able to overcome the problem? I would appreciate any suggestions. Thanks, Kent.