Boy Neil, that's really very unusual for a carbon comp resistor to go low, I've never seen that. All of the carbon comp resistors will eventually increase in value due to natural aging.
Although it is not often that I find a bad tube, all those tubes are available NOS at a very reasonable rate from many of the tube vendors like Radio Daze, Antique Electronics Supply, Tube World, Vacuum Tube Valley, Tube Store, Playthings of the Past, if your really in doubt about the tubes why not just re-tube the entire radio then you will have eliminated that as a problem probably for as long as you own the radio.
Denny G
