It appears the clank is gone but not the rattle. I don't see that there's anything else to be done other than use thicker grease than the official SA stuff, which probably isn't a good idea. The noise is within a tolerable threshold now but not nearly as quiet as my X-RF5 hub, which makes me wonder whether the newer hub designs are a bit better or if it's to do with manufacturing tolerances at the time the specific hub was made.