My turner has them big end up so I'm not familiar with that type of turner. What color egg shells do you have? I have a rally hard time telling on my Ameraucanas, OE, or BCM because they are so dark. I personally go with the philosophy that if I can't tell 100% and they are not smelly then I keep them in. I've done the other before and their were live babies in them.
I have several Marans eggs. If they don't glow like a real dim lamp shade their good. My EE eggs were very easy to tell.