Hello Ralph,
I have this problem too and have done pretty much everything to get them to stop. What seems to be working (somewhat) is advice a hatchery owner told me at a conference recently. He said I needed to break the chickens of their bad habit, which he think started when they accidentally cracked an egg in their early days. H said to trim their beaks with dog nail clipers to get rid of the sharp point/overhang on the top beak. No, this is not de-beaking! I tried trimming just the tips and I had to do it twice because the first time i think I was too nervous to do it right but now after the second time less eggs are cracked and not every day. To be honest I don't know if this is really helping or they are just taking a break from their behavior, and i still check for eggs like 4-5 times /day but I figured you could give this a shot. Just make sure you get someone strong to help you hold the chickens so you can trim the beaks at the right angle.
Good luck!
