Panasonic Quintrix F TC-21P50R help diagnosing the problem

[Sultanpepper]

Hello everyone, I've had this for more than 20 years so it's quite sentimental. It was stored for a couple of years in storage and then we moved to another location and as you can see in the videos this was the surprise. I'm still trying to gather information and watch alot of videos to be as ready as
I can before opening the back as I am aware there are alot of hazardous areas back inside. BTW I've got the service manual.

The Problem :

TV is flickering and colours are not aligned (convergence issue ? ), not all input channels (composite/RCA) act the same and the Component Input acts differently I think. The video will speak a thousand words I'm sure.

Videos from each input channel

1- AV1 (Composite cable from a PS1 ):
https://www.youtube.com/watch?v=6lfxpImx8yE
2- AV2 (Composite cable from a PS1 ):
https://www.youtube.com/watch?v=LHWeE9C8_nE
3- AV3 (Composite cable from a PS1 ):
https://www.youtube.com/watch?v=x0LMW_M6MHc
4- DVD (Component cable from a OG Xbox ):
https://www.youtube.com/watch?v=FgS4MNPdFKM


TV Model : Panasonic Quintrix F TC-21P50R
Service Manual : LINK

I would really appreciate if any one would help me in sharing his/her thoughts on what are problems I'm having and where and how to fix them that would be really appreciated.

Background : I'm always looking to learn new things and in my free time I like to buy and fix broken stuff which is quite therapeutic. I have no former knowledge in fixing CRT's but I always research before I get my hands dirty, of course I would greatly appreciate if someone guide me to a basics/FAQ for troubleshooting CRT's that would be quite beneficial and fun I imagine.

Best regards
SP