May just be easier to get new bushing and screw if needed. Stake the new bushing before attempting to reuse the grip screws. The bushings are intended to be mechanically staked into the frame (or at least the original and many of the clones) so that they don't come out.
Sounds like the existing bushing (stud) wasn't staked in properly.
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All data is flawed, some just less so.
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