I new this was a common point of failure and even bought some replacement sockets. Unfortunately, the break didn't reveal itself until after I wired the PCB back in
I globbed a little solder on the break and it's restored continuity through the PCB (for now). If I ever need to pull the PCB for some reason, I'll replace the socket.
I still don't have continuity through to the AC plug though.
There seems to be another break somewhere between the CRT and tuner tubes.