On delta tubes typically one end of all G-2 controls at abt 250VDC.
The other end is also tied together at apx 900V "BOOST".
Check the 900V with a 1KV meter !!. Probably the G-2 are at
abt 400V. Normaly a strong jug will quickly give you the line.
Also look at all the CRT voltages to be sure they are OK.
It may turn out to be all the same cause.
73 Zeno
LFOD !