I have noticed a trend in this hatch and a friend of mine noticed a similar issue in her hatch. We are (did) hatch in cartons and have noticed that one side of the incubator hatches out the eggs better than the other.
The side of mine that has the fan blowing gently on the eggs (I can see a tiny feather blowing on the shell of one egg) Well those 5 eggs haven't pipped yet.
Is the fan slowing them down, drying them out? Hmmm the whole right side minus one egg has pipped. They were all alive when I put them in there.
Don't you think this is a little odd? I think it is a fan/temp issue.