I bought a bag of wooden popsicle sticks, which I use in situations like yours & trimming of glass bedding that's oozed out but not fully hardened yet.
Cut a stick at an angle, near one end, and use the sharp bias cut as a scraper that won't harm bluing and the point to dig out threads and engraving.
Your fingernails won't take a beating, and the dried tread locker will still pop right off.
Toss the cut stick when it dulls, splits, or you're done - since they're almost as cheap as dirt.
I bought them in a store's cooking section - the sticks are used for making freezer ice pops for kids.