[Charlie]

Thank you, Phil.

Electrostatic focusing sets use the little rings with tabs for centering.

Magnetic focus sets usually have devices on the focus coil for centering. Sometimes it's a rod that moves around or spring-loaded screws, or a lever at the top of the focus coil that makes your adjustment. The hole of the focus coil is a little larger than the neck of the tube so it can be moved around a bit.

On this set, there's no rods or levers, but the mounting screws can be loosened for a good position of the coil. Usually, I wouldn't mess with something like that because I figure it was likely in the position it needed to be in already. When I looked at the coil closer, I noticed it looked like it was tilted downward a bit, and when I touched it, it moved the other way... and then brought the picture closer to where it needed to be.