[Eric H]

Do you mean it's a double pole trap, wired to the set with one large coil and one small?

It does look like the Focus coil might be off, that also controls centering.
The trap is in the right place where it makes the raster brightest, the Focus coil is adjusted after the Ion Trap.

There is some interaction between the Ion trap and the Focus Coil so you may have to go back and forth.
Also make sure the Yoke is slid tight up against the bell of the tube, not just the rubber bumpers but the Yoke itself, if you loosen the wingnut you can slide it forward.

If the Ion Trap or the Focus Coil is on backwards (front to back) it will cause problems also, the small coil or magnet on the Ion Trap goes to the front of the set.