If it’s smooth circular yellow yolk, duckling with its egg half (if still in) go in “chick in a cup” in Hatcher orYeah it is yellow. No, I didn't assist other than placing egg onto the floor of the incubator. I did this very quickly so the humidity wouldn't be altered. And the humidity is still in the right range. The bird did all the work of getting out of the shell.
Incubator. Danger is the ducky will step on yolk sac and rupture before absorbed so you keep them as quiet/confined as possible. This is in that assisted hatch link.