I've read in several places that if chicks don't make it out of the egg, the best thing to do is to leave them to their own devices whether they live or die because most chicks that are too weak to get out of the egg aren't going to thrive and are prone to all sorts of problems. Poultry that is weak getting out of the egg will throw chicks that have the same problem, so I know in breeding operations they don't try to "rescue" babies that don't make it out of the shell because it weakens the entire line to do it and results in less vigorous hatchings and more dead/weak chicks.
That being said, if I knew a baby was alive at one point trying to get out of an egg, I'd be hard pressed not to go in and try to save the little guy whether he/she was a "runt" or not.