there was a thread on dispatching chicks recently. i think pliers to the neck was one of the methods recommended.
its very rare to hatch out eggs and not to lose something.
my best hatches were when i have left them alone totally, as im sure lifting the lid and peeping effects humidity etc. transferring from a incubator to a hatcher would maybe reduce losses but you would have to hatch out alot to justify that investment maybe.
i never solved the problem with slow hatchers or saggy bums tho