One of my bathrooms has a clawfoot tub with a faucet similar to this:
Over the past 6 months a slow drip has progressed into pretty much a steady stream.
I've taken it apart the best I can but I couldn't figure out how to fix it (unfortunately there is no shutoff so I had to reinstall it). I was expecting to find an o-ring or seal that could be replaced but I didn't find anything.
I also can't seem to find any tutorials or resources online explaining how these valves work and how to fix them.
I would just buy a brand new one, but as you can see they are ridiculously overpriced!