Particular CRT spot size

[Alex KL-1]

This confirms my suspicion...

Apparently, I was misled by the tube shape of this equipment, which made me assume it was just a cheap B&W TV tube being used by the maker for this equipment model (since is a tube for magnetic deflection). My testing showed me is not the case; and really have a lot of halo in the lines/bright zones as you described, acting more like a oscilloscope CRT.

Ohhh, my project was cancelled...