I only have one hen and one rooster at this time (thanks to racoons). My hen or rooster is breaking the one precious egg I get a day now. Any way to get it stopped? I didn't have any problem until I was down to 2 hens. I found one of them dead in coop & for a few days no broken egg. Then it started up again. Usually the white and yolk are still in the remaining shell.
Is it possible that the shells are very thin/fragile? If that is the case, then work to get more calcium and vitamin D3 into your hen's diet. When I had thin shells, I ground up egg shells (pulverize in the food processor to a powder) crush a vitamin D3 pill, mix that with good high quality layer-feed that contains the max calcium your feed store sells. take this and mix up with the contents of the egg with the damaged shell. The raw egg will hold the powdered eggshells and the vitamin to the feed and make a substance your hen will eat with relish.
If the problem is egg pecking, then check out bumper bits. -- I will be back with a link.
Here is a link to bumper bits aka bumpa bits, you can get them on eBay from the UK. They are plastic and not only prevent the chicken from pecking other chickens, but also prevent them from being to break into eggs. https://www.backyardchickens.com/t/673137/device-to-stop-pecking#post_916192
HTH.
