Rule #1: Don’t. Unless. But mostly don’t.
Sally Sunshine explains why, how it probably doesn’t need help and you are likely to kill the baby trying, and provides detailed instructions in case it really is necessary, right here. If you’re currently watching a chick struggle to hatch, and think you might need to help it, please read that link.
It is rare, but sometimes helping is appropriate. Today was one of those days. Mama hatched five eggs beautifully yesterday and today. Another died in the shell (more on that in a later post: Warning, it’s graphic). One pipped in the wrong end, zipped partway, and got stuck.
Following this video, I gradually chipped shell away, and cut the membrane (it was dried out and not active, which means there were no live blood vessels in it–a critically important positive sign when helping a chick). I followed the same line the chick would have if it had been able to continue to spin in its shell. Then we stuck it under mama and waited.
Several hours later, it was still struggling, and exhausted. I pulled the shell open slightly, but not all the way, and put it under her again. An hour later:
Now Mama’s got six!