Bush TV135R

The PFL200 video amplifier screen grid decoupling capacitor is an electrolytic, originally mounted next to the valve. It dries up with the heat and goes O/C.
Manufacturing modification is to mount the replacement on the print side of the PCB.

p.s.

Should also add the fault when the screen decoupling cap goes on is poor or no frame sync, there is some LF degrade in the picture but the frame roll is the most noticeable..