The banding is occurring when raster engraving. I have a ULS 6.60 and am having no success with resolution of these symptoms. I do mostly acrylic engraving and use a very light etching for best light absorbing for my signs. The issue is more prevalent in larger engraved areas. Etching in shades of gray also exhibit the same behavior. X arm had been replaced, x motor and the bearings have been replaced.