That sounds to me like you need a washer. Loosen the nut, remove the hub add a washer and tighten. If there is no front to back play the splines are fine. You tighten the nut and it still plays tiny bit after its tight, then I would add a washer a little thicker than what you have for play. This should, help with not having to reef on the nut so much to make it tight as well.