Ekco T368 TV’s and similar chassis.
The 30PL13 frame output was run quite hard, in fact the screen grid in many could be seen glowing red even when the set was working under correct conditions. The circuit states 175v on the anode, 190v on the screen grid.
A mod I used to do was fit a screen grid feed resistor, about 1K and a 16uf decoupling capacitor. The cathode components were checked and replaced if required.
This slightly reduced the height but there was more than enough to compensate with the height control. The mod stopped the screen grid from running hot and greatly prolonged the life of the 30PL13 valve.
The mains voltage in our area was nearer 250V than 240V, this may not have helped but other parts of the set had reasonable life.