It sounds like they are fine. They will pip internally but they are still absorbing the remains of the yolk. That will continue up until they start to unzip. They are usually internally pipped for 24 hours, sometimes a little more, and the falling levels of oxygen stimulate the chick to pip externally. Then they will continue absorbing the yolk as well as the remains of the blood that has been running through the veins in the membrane until they are ready to unzip which can take anywhere from 12-36 hours. Every step is very important for the chick and interfering too early by trying to help them hatch almost always does more harm than good. Sometimes it is necessary but generally you just need to be patient and let them do it by themselves.