No HV on Zenith 23XC36, HO red plates

[Carmine]

I'm clearing out some old sets (BTW, Sanjar came and got that Maggie) and years ago I shoved this old Zenith with a beat-up cabinet aside into my basement to be basically a "parts set" for some nicer examples I own.

When I put it away, it was in working condition. Now I want to save the chassis and dump the cabinet/CRT, but first I wanted to be sure it still worked. So I fired it up, and no HV. After a few extra seconds, the Horizontal Output starts getting red.

I cannot recall if this is a symptom of a bad HO, (6JS6) or a bad HV rectifier (3A3A) (or both) I think a bad HO always kills the HV rectifier? I'm rusty.

Which tube (or both) would you sub? Is this likely just a tube? Like I said, worked OK when put into storage years ago.