I think once it starts to zip, it should finish within 45 minutes. It can quit if you open the incubator while it's pipped, or the humidity drops too low, they can get shrink wrapped. They can be mal positioned. The air cells might not be in the right spot (especially with shipped eggs). There are other reasons, but I can't think of them right now.How long can a chick stay zipped before it needs help. Is there a reason why a chick pips but can't finish hatching by its self. It always happens to me. I just need some advice please.