From my experiences, helping out is usually a terrible idea as the chicks will often come out weakened or deformed and I often end up having to cull them anyway (which is very unpleasant). That said, I've had a few successes and only after 24 hours of ZERO progress AND after all the other pips have hatched. As a last ditch effort I would chip away gently some of the shell and help it zipper itself, very gently tear the membrane and if there's even the slightest hint of blood, put it back immediately. I let the chick do the kicking though, just to make sure it's strong enough to possibly survive.
But honestly, for myself they survive maybe 2 out of 10 times.
Good luck, whatever you choose.