240 ma sounds a bit high. If you are riding it high you may be drawing
too much beam current. See what it measures at reduced brightness.
HINT ! You should be able to turn down the brite, contrast & color
level & extinguish , or almost so the raster, with no retrace lines.
CASE HISTORY. The Admiral M10 chassis was there first SS portables.
It used 2 beefy pass transistors in //. They ate them up often. Turns
out that if the brightness limiter was not set right you got too much
beam current but a normal pix. Over time it stressed things out then boom !
They short, & goes into HVSD ( pulsating on / off ).
BUZZ. You need to to balance the quad coil, buzz control AND the AGC control for least buzz. DO NOT use the AGC as a contrast control !!! In most cases the buzz can be eliminated or reduced to a slow & less annoying
tic-tic-tic on some scenes. I would also do this with a NOS 6BN6 / 6Z10 .
Time for another ale
73 Zeno
LFOD !