I'm going to guess the original flybacks were much like the old K7000 (white knob) ones and that they just do a wide array of bizarre shit when they fail. never saw a cracked flyback until this 33" Polo one took a shit, it had a 2 inch long crack in the side of it. luckily I was able to just cap that and I pulled a working one off of a free chassis I got and it was all good.
I hope your neck socket has the flip open cover for the focus wire, there's 2 designs of this and one of them, I can't figure out for the life of me how to open the damn thing.
they're pretty finnicky when the caps are starting to go bad. it's the best insurance policy for the Polo really lol.
pay particular mention that the replacement flybacks for these have a different color scheme for the wires, and some of them either have the extra ground pin or they don't. I installed the flyback on the last Polo I did incorrectly, I matched the colors of the original one and wound up soldering the G2 wire to the focus and the focus to where the G2's supposed to go lol. I'll have you know, the focus wire is the fatter of the two. remember this, otherwise you'll get some rainbow colored lines and a weird buzzing sound.