There is only one B5 terminal. I guess you mean the upper and lower holes in the terminal? If they read different voltages, then something is not connected - i.e. not soldered well. Since the plate load resistor is soldered first, it's probably in the lower hole, and it reads 77 volts, within spec - it's probably OK. However, the coupling cap between stages (0.1uF) apparently reads near zero, indicating that it is not soldered well to the terminal. That would mean that it cannot carry signal to the second, power stage - hence low volume, no bass, and likely an intermittent (scratchy) contact.
If the terminal seems to have too much solder on it, remove the solder (either the wire braid stuff or a solder-sucker) and start over with clean parts. But if it looks short on solder, you can just make sure the wire AND the terminal are both hot enough to melt solder before removing the iron, by touching the solder to the terminal and again to the wire, melting a bit each time. The solder bits should then flow together and you'll have a nice joint.
Of course I may have mis-interpreted the post - words are a poor substitute for actually seeing the thing!
