Pin nock fragility - any recommendations?

I bought a set of large groove Easton pin nocks a few months ago and have shot them maybe 200 times each. I've noticed nearly all of them have a large crack developing in the same place on the side that doesn't have the L, and about half have a much smaller crack starting to form underneath the L. Except for one, which likely bent during my release, arrow broke between the release and hitting my soft foam target.
The nocks were new and in their original package but several years old from a...

Pin nock fragility - any recommendations?