Troubleshooting HV section of a Tektronix 7904 scope --- Help needed

[rodd]

Dear all,
I started trubleshhoting this scope and the symptom was a blurry trace.
Than, after some time, I heard some clicking noises and  the trace disppeared; there was just a faint glow on the CRT.

I removed the HEPS and found a dead transistor in the regulator board (Q1451) which was part of the +15V rail.
Then, I reconnected the HEPS to the scope with the HV section disconnected (one lead of R1606 and R1603 lifted) and checked the voltage rails in the Z axis board test points- all were spot on.

However when I reconnected the HV section, the HEPS went to ticking mode, so I think there is a problem in the HV section

Since it takes a lot of work to get to these boards, is there any other component that is prone to failure in the HV section?
I have tested the two 22 meg resistors (in circuit) and they were fine.
I intend to replace the diodes and capacitors in the autofocus (CR1653/1656/1655/1658 and C1654/1656) and in the HV regulation loop (CR1676/1679/1680/1682 and C1678/1680) as was suggested in other threads.
Should I replace the HV diodes CR1607/1608 as well. If affirmative I wil use 2CL73A as replacements.
I will use BY206GP (350V, 1A, 1uS recovery   ) as replacements for the FDH5004. Is that adequate?
Since it is not a Tektronix dedicated foram, I have attached the schematics for those who try to help me. HV section & CRT 070-2390-00.pdf (1503.66 kB - downloaded 27 times.)
Thank you all.

[BlownUpCapacitor]

The 7904 is notorious for tantalums being shorted. Check the resistances of the power rails.

https://www.eevblog.com/forum/repair/tektronix-7904-repair/

One of my previous threads has resistance of power rails so use that. Find a rail that has a low resistance. There is likely a bad tantalum on that rail.