R707 is there as a fuse, so if it opened up there is a hard load on the
200v line somewhere.

The diode simply rectifies the ac pulses coming off the flyback, make
sure it measures like a diode and is not shorted.

Odds are very high if you simply replace the fuse, er resistor, that it
will go up in smoke as soon as the set is powered on.

You can at least narrow down the problem to a specific crt pcb by
disconnecting the 200v line from each of the crt circuit boards and
then making resistance measurements of each crt circuit board between
the 200V in and the ground to the crt pcb. I am betting that one of
those will be very low. Then it is a matter of finding the video
output device that has shorted on the crt pcb.