If the socket in question produces no sound with any tube, you've almost certainly blown the screen resistor on that socket. Try the tube in question in another socket, on its own - if it also works, the tube is OK.
If you have blown the screen resistor, the amp only appears to be working OK - in fact, it's running at half power on one side of the waveform. At lower volumes you won't notice this but as you turn it up the amp will start to sound odd and a bit low on headroom.
Blowing the screen resistor will happen if the tube filament - normally between pins 2 and 7 - gets connected across pins 4 (screen) and 1 (ground), if the tube is two notches out of position, or between pins 4 and 7 (filament, but also effectively grounded), with the tube three positions out the other way... because the filament is very low resistance, it will draw a large current directly from the high voltage supply to ground via the screen resistor, and is also what causes the loud hum. It could have been worse - one notch out and the filament is then between pins 3 (plate) and 8 (also ground) which can blow the output transformer.
For future reference, any time you change or replace power tubes in any amp, *always* power up with the amp on standby, and then check that the tube filaments are all glowing correctly *before* flipping the standby off. There is only one orientation where the filaments light up, so this shows for sure that the tubes are the right way in. This doesn't work with rectifier tubes, you have to be extra careful with those since they're ahead of the standby switch. The odds are the same though - 1 in 8 correct; 4 in 8, won't work but probably no damage; 3 in 8, something dies!
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