I am not an expert, but I will share my experience with my one time hatching duck eggs. It turns out I had a faulty incubator that wasn’t keeping the proper conditions and my ducks needed assistance in hatching. It was daunting but once I did it, it was pretty easy. In the air cell I took a small but sharp screw and gently scratched the surface til I was able to create a small pinhole. Those shells are a lot tougher than you’d think! After that I waited, as at least it could breathe, but still no pip on its own. So for four of the six eggs (one died in the shell and the other stopped developing early on) I took a pair of sterilized tweezers and very slowly and precariously started pulling shell away from the pinhole. If membrane was visible I’d dab a little bit of coconut oil to keep moisturized. I stopped picking shell away when it was about dime sized or slightly larger if they still struggled. They ended up hatching the rest of the way on their own.
