I'm not a helper when it comes to hatching but once I had a chick that had zipped the egg but not broken through membrane in doing so. It had just pushed the shell off all around. Well it was stuck in there for ages and ages and in the end (as it was the end of hatch) I broke the membrane for it and let it hatch. It got out in the end but was a weak chick, it didn't thrive and a couple of days later I culled it. There was obviously something wrong with it and in nature it would never have made it out of the egg. That's why I like them to hatch on their own with no help at least you know then you have strong chicks.