Never turn eggs end over end. The air cell needs to always been pointed in the upward position, at least the large end higher than the pointed end of the egg even a little bit. The ideal way to turn eggs is from side to side. The idea behind turning the eggs does a couple of things. It helps to keep the yolk centered, turning makes more food available that has been previously consumed by the growing embryo and it keeps the embryo from sticking too long in one position.
If you can't rotate from side to side, can you tilt the eggs at all? Even the slightest tilt on the egg will do wonders for the growing chick. Even twisting them every few hours works as turning. The more you keep things moving around on the inside, the more nutrients become available and helps the yolk stay centered.