You can often just flush and lube the freehub body after it's removed from the hub and it will work fine. Not knowing exactly which freehub you have I can't tell you the exact procedure but no need to take it apart as it can be done while it's assembled. Check some how-to YouTube vids. The wheel bearing balls are probably fine but eyeball them for damage and they are cheap enough to replace if you just want some peace-of-mind.