Wiltron 6409 (2GHz RF Analyzer): CRT fault

[auato]

Hi all,
I am facing a fault on a CRT board (KME MB22) but hard to troubleshoot as it's not available the electric diagram. As you can see below in the video, from time to time, the horizontal driver shuts down for a while.
I already tried to move horizontal inductor trimmer, tried to check the solder jonts and replaced the electrolytic caps. Power supply voltages seem OK, as well.
There is a red wire starting from the PCB and labeled as "A1" towards the pin_base of the CRT on which I found high voltage (about 450-500Vdc) and everytime the defect appears it goes down as in this video https://youtu.be/To5Zq-NKuFY

What do you think?

Thank you

[BrokenYugo]

Check the solder joints again, with magnification, pay extra close attention to large pins and anything that gets hot. Or flux and reflow everything to remove all doubt.

[fzabkar]

Tap test, heat with hair dryer, cool with spray freeze ...

I always reflow the solder at inductors and transformers.

[auato]

I have "reflowed" everything (sucked old tin with braid and resoldered) but the problem persists. Noticed this vaweform on the flyback transformer. It is a 7 pin flyback but, as already wrote, I don't have any schematic diagram and I am not expert on this type of circuitry at all

https://www.youtube.com/shorts/wFde63Su4PM

[james_s]

The HV transformer is part of the horizontal scan circuit so if the horizontal shuts down then most of the voltages will fall. Can you tell if that's what's happening?