Is there any easy way of knowing where the vertical output section is?
I took the back off the tv, and was hoping it would be marked "vertical
output", but it doesn't appear to be...

It's a Hitachi CPT 2224

There's a small circuit board attached to the very centre of the back
of the screen, there's two solder joints that look as if there's a hole
going through them. They're marked GND and K1.

Thanks!