It can take a day or even 2 for a chick to hatch. It may just be tired and taking a break. As long as you hear/see that the chick is alive, its usually best to just wait.
Be sure your humidity is high though so the membrane inside the egg that is around the chick doesnt dry out and trap it, preventing it from moving and hatching.
Personally, I have helped chicks at the end of hatching, others I have let do it themselves or die trying. I have had sucess with putting a warm, wet washcloth under the hatching egg, which seemed to help it and get it to hatch out fairly quickly after a long attempt to hatch.
Problem with helping is, its sooooooo easy to tear a blood vessel and the chick dies of blood loss before it can fully hatch. Another issue is, the chick needs to struggle to absorb the blood in the membrane vessels AND to absorb the last of the egg yolk into its abdomen before fully hatching- an too early intervention can mess up that process and usually will end in death to the chick.
If you do decide to help, go slowly, and be ready to put it back into the bator if you see any blood, and keep a warm, wet washcloth (wrung out, not dripping wet) at your side to put the egg on (inside the incubator) to help keep it moist. Keep an eye and ear on it!
Keep us posted!!