1950s or '60s vintage Zenith TVs, Need some info

[vortalexfan]

Originally Posted by old_coot88

First, you might want to see if someone's put a shunt resistor across the 3BU8 heater (pins 4 and 5). It'd be a low value resistor, something like 20 ohms. Without the shunt for protection, seems like the 6BU8 would be lighting up like that 6CB6 did.

It was a 3BU8 after all, the way the dirt and grime buildup was on the tube it made the 3 look like a 6.