The way it works:
The GEO belt has only so many orbital points (it’s finite), and those assignments are assigned by the International Telecommunication Union (ITU)...a (shudder) agency run by the United Nations. Once the satellite is no longer in use, it gets decommissioned and sent to a disposal orbit out of the GEO belt, and the slot is available for re-assignment or retention by the country that originally applied for it. In this case, it looks like it was moved to disposal in the 70’s after the comm went out.
For additional information...
https://www.itu.int/ITU-R/go/space/en
