[John Bartley]

Just a thought .... All the B+ readings are low, except at the rectifier .... in other words, on the rectifier side of the field coil the voltages are ok and on the radio side of the field coil they are all uniformly low. My first suspicion would be a defective field coil. Maybe try a quickie test of paralleling the field coil with a 1K resistor, just for a second to see if the volume improves. Alternately, you could stick a DC ma meter in series with the B+ coming from the field coil to see what sort of current the set is drawing. If it's too high you will end up with a voltage drop such as you have.