Does it allow for different spacing between the roll bars for difference egg sizes? If I'm understanding correctly they are moving from horizontal to more vertical as they roll towards the left or right, I would think that's due to the shape of the egg (or as others stated a non level surface). I have a similar problem in my NurtureRight360 when I put quail eggs in the chicken egg turner. Swapping them around (with super clean hands) frequently is a good idea anyway because even the best incubator has hot and cold spots. If you notice swings in humidity when you need to rotate you can spritz just a bit of water on the wall of the incubator bottom, but if you're fast enough it should recover well enough on its own. I would personally change the orientation of the eggs and see if that helps, just to be super clear, if they're all facing right swap them to all face left and see if that helps. Good luck trouble shooting!