The horizontal section has two ICs, an
LA7850 for deflection and an
HD74LS86P which is four XOR gates. It's mounted on a little card with a few passives and four wires going to the neckboard.
There's a cap (C427) which lives right next to the LA7850 and H-hold adjustment and it looks like the type that cracks and smokes. I totally forgot what it's called