Leaking fireplace globe valve

I have a globe valve on the floor by my fireplace which operates with a key. When closed, it seals completely. When open however, it leaks around the shaft. I suspect that the packing has deteriorated in the 90 years since it was installed.

I am curious if it is possible to repack this from the top.

The floor plate is labelled "United", which may have been the United Brass Mfg company in Cleveland when the house was built. I've attached a couple of pictures.

Any help would be appreciated.