I think it could be a fertilty issue
From the quail breeding pen escape/attack/loss.
I havent used my smaller candler on them. Yet.
I did see a few with veins though.
A dollar a chick they should fly
CHEAPEST I seen a day old quail/cot is 75 cents
Usually 2 bux
Chickens usually 2-8 bux
really like my rechargable flash light. It stays plugged in 24/7 and will turn on in a power failure . It is the right size to black tape the end of a roll of foil on to it. .