The vertical on the CTC-16X seems a bit strange
Height Pot is normal enough, B+ 390 (1) via r104 through pot r14 to gnd.
It's linearity (r13) that's weird, high side from 970v boost, but then the other side goes all the way to s6 (picture tube bias ) and then to screen grid pots ( via r193 194 )
not really sure what they are doing with this