Zener diode is in the 24 V source. 103-105. Also a 2 ohm 2W.
They are mounted behind the chassis either on a little
PCB or hand wired old school style depending on year. The 24V
transistor is on the chassis facing you. 121-992 IIRC
Zener would short & open the 2 ohm killing the set.
If the transistor shorts you get 2 white hum bars like a bad filter.
The 130 V is more likely. If the oil fillled cap opens there is
no regulation & the pix pulsates badly. Could explain the tripler
also but a lot did just go bad.
73 Zeno
LFOD !