Are your other eggs on day 18? And are you doing a staggered hatch in one incubator? If so Id stop turning now and leave the lid shut and let them hatch. If you have no external pips then the opening of the lid that you have already done wont cause an issue. Once external pips start the lid NEEDS to stay closed to keep the humidity up otherwise you risk shrink wrapping the chicks.
It can take up to 24 or more hours from the first pip to zip to hatch. Pipping is the first crack in the egg shell, zipping is when the chick will make cracks in a line all the way around the top of the egg so it can pop off the top of the egg and hatch. It takes time and lots of energy from the chick so he will rest often. It will make its out on its own just give it more time. And sit on your hands lol no touching the eggs.
