I'm using a Truturn prop hub and as it turns at idle you can see it turning out of round. I thought it was my imagination at first but my friend noticed it too. When I put on just the hub and rotate it with just the hub you can feel the hub go up and then down. You can also see it in the prop rotation. Very strange indeed I admit. I'm perplexed. I may have to get a dial indicator to confirm it though.