From the pix the focus itself seems to be good.
There is a focus coil. You can adjust it to see if
it focuses best in range. If it goes to either end &
focus getting better but not good may be a bad
focus rectifier.
Seems to have good width so if its HV related its
probably the 6BK4 or 3CU3. If you pull the 3CU3
grab it at the cap end, you may get bit near the socket.
Also the big plate cap for the 6BK4 has HV on it until
discharged.
If HV is OK brite prob. could be adjustments, video problem,
boost problem or CRT.
73 Zeno
