There is clearly brown greasy looking crud on the socket.
See if you can clean it up with a swab & 91% alky. Be sure to discharge HV first but the divider probably bleeds it off anyhows.
You may want to search e-bay for a NOS HV cup.
73 Zeno
LFOD !
Will do. Any advice about the metal rivets? Is it avoidable to drill them off or is that they only way if I need to replace the HV cup?