[stevehertz]

Personally I don't use abrasives on chassis, I clean them up using a rag and cotton buds for the less accessible areas, then wipe any rusty areas with a small amount of oil, changing the rag surface until the area changes from brown to black. I leave a small amount of the oil in place to prevent further rusting. If that method is not 'fine' enough for your desired appearance, then a complete strip down and repaint or re-plaiting will the job. The former method may be less than an hour, the latter several weeks.