[mkharks]

I have a Philco 40-180 that I had restored electronically.  It plays well for awhile, but after a few minutes, volume decreases significantly (almost inaudible).  When I turn up the volume it sounds fine.  However, the volume will eventually go back to the original level (loud) and need to be turned down.  It cycles back and forth.  I think it could be related to the 84 tube.  When volume decreases, I can tap/move the tube a little and the sound will go back to normal for a short time.  I replaced the tube just to be sure, but see no change.  Also, when volume decreases, I can turn the set off and immediately turn it back on and this seems to reset the volume to the correct level.  But again, volume will continue to cycle.  I am hoping someone on this forum has insight into this issue.