Is it ok to keep opening the incubator ? How can I keep an eye for any others struggling? That bit I swear is the leg ... but maybe I’m wrong, but I looks like the bend in it’s leg as it has that type of scale look pattern x
Just keep watching thru the window for now. Hopefully you will see some movement, or even opening and closing of the beak.
If the others have pipped normally, I wouldn't bother with any of them yet. I use a magnifying glass, and watch the pip hole membrane, or the shell chip, watch for any slight movement.
Do any of the yellow areas look chunky, like wet cheese?
(sorry, can't think of a better description LOL)
EDIT to add - peck on the window. That will usually get a reaction. Or flash the light back and forth across the pip hole