My original Leader Grips have developed some cracks, but they're at least 10 years old. The first few cracks were because I tried to push then on over top of an existing (smaller) clip that was anchoring the quilt backing.
I couldn't find replacement ones locally, the store that sold me the original ones closed. Shipping was cost prohibitive to my house (Canada).
I bought a different product but I haven't started using it yet, I'm still using up my Leader Grips.