Repro center cap issues

Just wondering if anyone else had an issue with repro center caps staying on? I bought a set of Wheel Vintique Police style rally wheels and their center caps. Center caps kind of snap on, but will come off with very little effort- certainly aren't going to stay on if I try driving with them. I had someone on another forum mention that there are spring steel clips that fasten onto the rim and will hold the center caps more securely- has anyone heard of something like this? Any other ideas to keep the caps on?

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