Horizontal/line sync issue...

[Alex KL-1]

Hello, folks of Videokarma,

Last days, playing with a tube B&W TV, I noticed that the H sync appeared strange, like with odd line at one position, and even lines just ahead or behind.
Such problem I already seen in the dynamic form, like this: https://www.hdretrovision.com/jitter even with VGA monitors.
But I never seen it static, i.e., with the lines simply not aligned. But not for all screen; the issue appears at upper side, and vanishes from mid to below.

The scenario of this TV is: the sync is separated from video using a 6CS7 multigrid tube, having a 1/2 6CG7 for making the complimentary pulses (a "concertina" inverter), folowed by a simple RC filter and the this follow to the AFC diodes.

I wondering if:

1 - oscillations in the video amp... but then the issue will be random?
2 - too much or too low pulse filtering?
3 - interference?
4 - oscillation in the inverter?
5 - bad quality video signal? (I'm not noticed this issue in others TV's with same equipment)
6 - bad sync separating? (when I checked this some time ago, was textbook perfect)
7 - bad AFC diode?

Note: with this TV, I'm using direct video input. And, the vertical sync are absolutely perfect.

Soon I want to investigate all of this. Meanwihile, if some people already have experienced this and have some light about, I will be grateful for any tips!