I just did a tube swap (with yoke swap) and I'm following a tutorial on purity adjustment. However, I'm having an issue. In the tutorial it says bring the yoke as far back as you can on a red test screen. Then you adjust the purity rings until all the colors are equal. The tutorial shows all colors filling the screen. However, on my screen, my blue is rounded in the corners. What's causing this and how do I fix it?
