8 inch RCA

[Eric H]

I doubt you can substitute another magnet, besides the physical size, this is a very weak magnet and a bigger one may not be compatible with the CRT.

The reason it has to be adjusted with the set assembled is that the metal shield around the neck of the tube can affect the magnetic field enough to throw the adjustment out of whack.

I fought a set for hours once because it would work when apart but not when assembled, it was the metal shield messing with the Ion trap.