I give it about a 70% chance it is the flyback.

It ain't the frequency, it is the waveshape that tells you.

Just to give it from the top once, you put the scope in 200Mv, 10uS
auto triggered. you put the probe near the fly, and you should see a
pulse, about 12-13 uS for a nonHDTV. If you do, you scope the vertical
windings of the yoke, put yout finger on the scope probe, take it into
freerun mode and use the vernier to sync it with the powerline pickup
from your body. Then you go to the yellow and green wires to the yoke
at 20V/div.

You should see a similar pulse but with a ramp on the end. It will be
moving, but you can still see it. If you do, you go to the main B+ and
set it to 50V/div and watch it rise, if you see it go over three divs,
suspect caps on the primary side of the SMPS or a bad opto or
something that drives it.

If the set is regulating properly, don't forget the audio IC, scope
the Vcc to it and see if it drops like a rock, if so, remove the audio
IC and try it again.

And never forget, if you get a ****ed up waveform out of the fly,
check ALL diodes connected to the fly, especially the big ones.

If all this fails, well it may be junk. Needing proprietary parts is
not an option. Aftermarket flys are out there, ome of better quality
than others, but when you get deep deep into the circuitry, it is not
usually worth the time unless the unit was expensive and hs as good
chance of having a good CRT. CRTs do not last like they used to, and
the old ones are old.

Off to bed.

JURB