The only problems I've had with egg-eaters, and it has happened with good hens that later stopped, seemed to have to do with the nest - not the eggs.
I better start off by saying that: my laying flocks do not have egg shells unless the shells are thoroughly crushed. Also, my hens have always had a high protein feed except long ago when I thought just feeding wheat to my hens was okay (they promptly stopped laying). I make sure that treats are kept to only about 10% to 15% of their diets.
The nest needs to be a "sacred place" for the hens. It should be in a quiet, out of the way location, and it should be clean. Do not allow sleeping in nests; that is a very bad habit and needs to be stopped. The easiest way is to block the nests during the evening. I had a nestbox near the roost, once. Struggled to get 1 hen to stop roosting in it - instead, I got an egg eater! Moved the nest and had no more problems.
Laying on the floor is another way to have eggs eaten. Sometimes, I have had to physically introduce a pullet to the nestbox to get her to lay in the right place. Minimum of disturbance . . . just try to show them what a
wonderful place it is. I would put up lace curtains and decorate with doilies if I thought it would prevent egg eating
.
The last time I had egg eating problems was when I let eggs pile up in a nest
. A hen may have broken one on accident. Anyway, don't do that.
Since I have used a tarp as a nestbox cover, there hasn't been a single incidence of egg eating. The nest isn't
completely darkened but I would be willing to take that step.
Finally, cull the hens if you can't get them to stop. I've never had to do that. Always, it seemed to be my fault
that egg eating occurred.
Steve