[Mondial]

One thing I would definitely do is add two DC blocking caps in series with the existing ones in the filter block. These are the .025 uF audio coupling caps between the tapped audio choke and the output tube grids. Any leakage here will throw off the bias and cause the output tubes to draw excessive current. If you connect new .22 uF caps in series with the green leads from the can, the resulting capacitance will only be slightly less than the original, and any leakage will be eliminated. I would probably leave the other bypass cans alone, as slight leakage will be of no consequence. You can jump across each bypass section with a new cap and see any change in performance, just to insure they are not open.

You might check the voltage from screen grid to cathode of the RF tubes and see if the screen voltage varies from a few volts to about 90 as the volume control is rotated. If so, then the volume control action is as it should be. If you connect a longer antenna, then the volume control may respond over a greater range of rotation. Also, anything which reduces the RF gain of the receiver (bad tubes, coils, alignment etc.) will require you to advance the volume control more than otherwise would be necessary.