How long has it been since you helped her get unstuck?
Do you see any red blood vessels in the inner membrane (the clear membrane that is right under the thicker white membrane)? In my experience, when they get their bills out like that they won't be able to finish zipping on their own, but you'll want to give her 24 hours from the time you helped to see if she can finish on her own. She might surprise you. You don't want to help her out too soon because hatching is a very precise process. They will not hatch out until they have fully absorbed their yolk sac. You'll know when that step is complete because there will no longer be red blood vessels filled with blood in that clear inner membrane that surrounds the duckling. Also, you might be able to look inside that opening and see if you see yolk or those red blood vessels in the membrane with a flashlight. Only do that when you're already opening the incubator to add water or moisten the membrane, you don't want to open it too often and lose all your humidity. That'll just dry out her membrane again and it'll stick to her, making it impossible for her to hatch out on her own.
Have you read through this thread?
It's very informative and describes exactly when and IF you should help a duckling hatch. There is alot of information there, just read through it and relax in the meantime. Hatching is a slow process, so don't freak out and help too quickly or too soon. Ducklings typically take a couple of days to hatch out once the hatching process has started, so there is no rush to help right this moment. It's always best if they can do it themselves, of course, but sometimes they do need a little help from us. It should always be a last resort, though.
Good luck and please keep us updated! :)