Very hard to know whats wrong here, unfortunately. Can't come with any advice except check all connections with your ohm meter (amp off). You can also measure the anode voltages (amp on). There should be about 80 V on the anodes of the 6AS7's. 100 V on the B+, then a 20 V drop across the 330 ohm anode resistor. Also measure voltages on the input stage. If all voltages are good you should have sound.