Help me detect blood spots in brown speckled eggs?

[StrawberryMoon]

I recently bought a cheap plug-in candler, hoping I'd be able to detect blood spots in the brown speckled and pink eggs I get from my faverolles. They have really thick shells, too. I can't see a thing inside these eggs, even with the light! Is there another method or a better candler that I could try?

 

[Chicken-lovebirdchihuahua]

Mine did that to I used a super high powered flashlight