We decided to make a video of how to deal with unabsorbed egg yolk. This baby spider emerged from the egg early, before absorbing her egg sack. So we put her in a little deli cup, but she didn't absorb any of it, and we decided to cut it off!
After few days her belly was closed and she shed just fine.
Then we tried feeding her, but she wouldn't take it, and about a month after her shed, we decided to force / assist feed her and she took the pinky rat the first time we assisted her.
The same thing you can probably do after you find a baby with twisted umbilicus.
The baby is now doing fine, and shes messing up her tub after the first meals.
Ok so here is the video of the whole proces!
Hope it helps.
This or twisted umbilicus happened (or will happen sometime eventually) probably to most of the breeders, but we didn't find a lot of videos of how to deal with it, so here is one more.