[Reece]

The volume control adjusts bias on the first two tubes so until those stages are working the control won't do anything. With the antenna on the detector grid, you get sound, so the last 24 tube and the audio output stage are OK. Now move your antenna to the grid of the tube just before the detector and ditto on each tube in turn working back towards the first stage. Where you lose your signal look for trouble in that stage: voltages OK? Coil continuity, condensers not shorted, resistors OK, etc. The 24's are OK upside down, but the 45's you want to be careful of as their filaments could sag and touch the plates and adios 45. But you don't need to play the radio upside down. Locate the stage you want to troubleshoot via the grid test, turn the set off, turn over, and check all components in that stage.