I had 3 out of 4 eggs in the incubator go into lockdown. Two pipped late day 19 and hatched day twenty. The last egg still hasn't pipped and it is day 23. It is a jumbo sized black copper marans egg whose air sac probably didn't get as big as it should have. (I adjusted humidity by the other 2 eggs) I hope the little guy isn't stuck or dead, it hasn't pipped internally yet. I am having a hard time waiting it out.