Picture tube capacitor (21FDP4)

[electroking]

Maybe it is broken and that's wise you need to replace it, but leaving the original
part in place might be your best bet. I trust if an ohmmeter check reveals a resistance value within spec, the part can be assumed to be good. There is
hardly any way a ceramic capcitor like this would open.

From the schematic I assume the resistor is a loose tolerance unit of 600 Kohms
+/- 400 Kohms.