Blue spark inside CRT neck related to focus

[Flybacks]

Hello, when I power on the TV there is a blue little spark inside the crt glass neck that increases and decreases in intensity with the focus, when focus pot is at minimum it is invisible when it is at max it is brighter and makes some dots on the screen appearing and disappearing randomly.
The picture is fine and the TV has no problems.

I've cleaned the crt plastic socket, pins and the spark gap contacts so I don't understand what could cause it ??

Some pic attached for better understanding.

Many thanks for your helping

 

[73's de Edd]

Sir Flybacks . . . . .

there is a blue little ? spark ? inside the crt glass
Its REALLY a BLUE GLOW . . . . that's been around for multi . . . . . D . .E . .C. . A . . D . . E . . S

In case you are not familiar with any tubes that have a vacuum PULLED on them . . . . this can occasionally occur . . . .

DA'BLUETUBEINNERGLOWPHENOMENON . . . . . . DONTWORRYBOUDIT !

https://blog.thetubestore.com/understanding-blue-glow-in-your-amp-tubes/


73's de Edd . . . . .

My goal for 2021 was to lose just 10 pounds . . . . . . now only 35 to go.

.

 

[Flybacks]

Sir Flybacks . . . . .

there is a blue little ? spark ? inside the crt glass
Its REALLY a BLUE GLOW . . . . that's been around for multi . . . . . D . .E . .C. . A . . D . . E . . S

In case you are not familiar with any tubes that have a vacuum PULLED on them . . . . this can occasionally occur . . . .

DA'BLUETUBEINNERGLOWPHENOMENON . . . . . . DONTWORRYBOUDIT !


73's de Edd . . . . .

Hello, this blue glow isn't occasional but occur for all time the TV is on and change intensity adjusting the FOCUS pot... I don't think it's normal.
And what about the random dots that appear on the screen when focus is set at max ?

Thank you