Just to let you know, #45 bulbs are for 3.2V, #44 are for 6.3V. The wrong bulbs might have been accidentally mixed into the batch. As for a slow fading away of sound, that is usually due to a problem with a grid leak resistors. I would check the value of the leak resistor on your power tube, and also that it is well grounded. Static could also be caused by poor grounding on the grid leak. Just a suggestion though. I forgot to mention that the screen resistor acts the same as the grid leak, in that it can also add static and drag the tube into cutoff.