My little call duck is sitting on 3 eggs (there were 4). Day 28 was 6/6 (and calls usually hatch before that, around d26). One kind of half hatched d27 but had a partially non resorbed yolk and died in shell. The other 3 still have good veining and seem alive but are showing no signs of hatching or internal pip even. What should I do??? How long should I leave them with her? Should I try and assist? It seems like they are stalled out...is there anything I can try? She's been a really good mom - sitting patiently with few breaks for food and washing. I just don't know what could be wrong 
