Lotsa dying quail.

[Nichrome]

I am no Vet but to me it sounds like a virus. Make sure bator and brooder are disinfected throughout with every batch of chicks. Feeding vitamin supplemets to the breeding flock did wonders for me too!

I read that you are leaving them in the bator. That should not be wrong as long as the ventilation is adeguate and as long as you gradually reduce the heat in the bator...but ventilation most of all!