Move any wires that go to pin 8 including the 18K resistor to pin 1 and install the 1 ohm resistor between pin 1 and pin 8. Hum can be from mismatched tubes or a bad filter cap. If the current doesn't match between tubes within 10% or so, swap the tubes between sockets to verify that the problem is the tube, not a problem with the socket. If the problem is with the tubes, try a different pair.