Well, I hatch ducks, so it's different. Mine will sometimes go 48 hours. But after that--I help them.
For chickens, I would say 30 hours is a looooong time. Personally, I'd start helping--but only a tiny bit at a time, in case it's still too early and the chick hasn't absorbed the yolk or shut down the blood vessels in the membrane. Are there other eggs in the incubator? If so, you've got to be careful about humidity. I wouldn't take the struggling egg out until the next time you are opening the incubator for some other reason, and make sure the humidity is nice and high before you do so.
The bird will be fine stuck in the shell for a couple days after it normally would have hatched, so you won't hurt anything by waiting until the next time you open the bator.
Then I would do just a tiny bit and try to see if the veins in the inner membrane are still full of blood. If they are, you'll find out quick enough when they start bleeding. This is usually not too dangerous if you're cautious, but if you see fresh blood, it's time to put the baby back in the bator and wait a few hours. You will naturally see some dark brown liquid that looks like old blood, and that's fine--it's bright, fresh blood you don't want to see.
Good luck!