CAG hen beak tapping in nesting box?

[CongoRock]

Our CAG hen has been sitting on eggs for the last two weeks, but has recently been making a knocking noise inside the box? Everything else is pretty normal, theyre in a quiet part of the house and she has only come out a handful of times in the last two weeks. Dad doesnt seem to be in the box very often, but we've given them some space since they both became very protective of the cage once the eggs were laid so he might be going in during the times we are not watching.
Any insight would be helpful, I've bred smaller parrots in the past but I have had a hard time finding good info online for specifically African Grays, so any online resources or book suggestions on their breeding/behavior specifically is welcomed.
Thanks for your help!

 

[expressmailtome]

@BrianB may have some insight on this.

 

[CongoRock]

After watching them on a camera we set up it seems like shes trying to summon dad because he usually goes in and checks on her for at least a minute when she starts up if theyre all alone.

 

[Emma&pico]

After watching them on a camera we set up it seems like shes trying to summon dad because he usually goes in and checks on her for at least a minute when she starts up if theyre all alone.

Clever lady ow come here