I had a box turtle chip a beak once.
Our vet uses a dremmel tool on beaks so I took the turtle in and all she did was smooth it out for us. That really helped because I think the unevenness of the beak was bothering the turtle.
We didn't have any problems after the vet did that.
That's something to consider, just get it smoothed out & make sure they're getting enough calcium in their diets.
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PHRatz