Duck stuck in egg shell?

[Lilybljm]

I have a mother call duck who has been sitting on four eggs. Three of them hatched on time, and two days later, another pips. That was late last night. This morning, i checked again, and the duck was almost completely out of its shell (its feet, legs, neck, head, stomache, and tail) were all out. I pulled away a very small peice of hard shell at the base of its neck, and six hours later it is still struggling with no more progress. should i assist its hatching? the mother is still sitting on it and doesnt seem to be of any help.

 

[AquaDuck]

If the shell or membrane is stuck to the duckling, then spraying it with some water will help.
Other than that, let it be, it seems to be doing fine.

 

[Lilybljm]

Update: after just under 24 hours, it managed to get out of its shell, however it is very weak and unable to jump into the egg boxes where the mother sleeps. In addition, it refuses to bend its back at all and is standing up straight and away from the others. I am still concerned about this ducks health and nothing online can seem to tell me the cause of the issue.