Meh, I'd go ahead and help it a bit. I think you said you made a zip line... make sure you've got the room warmed, and have warm water + q-tips at hand. You can use tweezers or something (I use a push pin) to crack away bits of shell and peel back the outer lining (the white one just under the shell) until you've taken the top 1/3 of the egg shell off, but left the inner membrane intact. You can then check it easily for blood veins. Wet the inner membrane while working, but definitely at this point you should wet the membrane down completely with warm water. This should light up any veins as red- if they are there (or if you see them on the membrane while working (just their presence, not blood from broken ones) then you should probably leave the chick be for a while. The presence of veins tells you that the chick is not quite ready, and is still attached to the inner membrane through its circulatory system. This should cease when it's ready to kick itself free.