The isolation of the pins from ground described suggests two open circuits:
1. between pin 3 & 4 of V4, perhaps open heater, dirty pins, broken or poorly tensioned socket pins.
2. between pin 3 of V8 and pin 4 of V6, perhaps broken wire, cold solder joints.
It is also possible that your probe was not making good connection to these pins due to flux left after changing capacitors.
jr