Nanao Ms9, with Toshiba tube, red spot issue

[Firehawk]

I have a weird issue which I don't know what can cause it.
On the left side of the tube I have a spot which is only visible with the red color. Spot gets pinkish or pale red. It's only with red, with other colors I don't see it.
The chassis and neckbord is recapped and cleaned 3-4 years ago.
In the picture you can see it near the letter R. Couldn't make a nice picture but hope you can see it.
Its also in other games when the background is red.
I already degaussed a few times but that didn't fix it.

Any ideas?

 

[BuddyC]

Looks like purity is a little off. Video below explains basic convergence and purity adjustments. Read up on CRT safety before doing these adjustments. Lots of nasty voltages you want to avoid.

He talks about purity around 3 minutes inn.

View: https://www.youtube.com/watch?v=faZiB7xZylU

 

[Firehawk]

Thanks, yes I already spoke with somebody else I need to check/adjust the purity rings.
Will look at it this evening if I can fix it.
This one has it worse but also a round spot near the side and fixed it with adjusting the purity rings. Will check it and come back.

View: https://youtu.be/xAvd2ef89X0?si=tm3gSDPu6P8pVmqy&t=197

 

[Firehawk]

It was indeed the purity rings. Adjusting them solved the issue.
Before and after pic.

 

[jcmorrisii]

It was indeed the purity rings. Adjusting them solved the issue.
Before and after pic.

great job!

 

[themisterfalcon]

Awesome work. It took me years to get comfortable with doing this myself. It's not easy to do or for the faint of heart. Congrats on the win!