Help troubleshooting reach adjust on Sram road levers?

I bought a used road bike with ~2010 Sram Rival levers. The levers are in good repair and work flawlessly EXCEPT the reach adjust is not functioning properly.

On both levers, the reach adjust bolts turn freely but the threads are seemingly not engaging anything. I can turn them endlessly with no effect on lever reach. The bolts don't rattle and won't come out so presumably a circlip or something is holding them in place.

Anyone have a thought as to how to fix this? The levers are at what feels like their minimum reach, so my fingers are pinched while braking.