MOST LIKELY, THE TUBES IN YOUR SET WILL STILL BE GOOD. REPLACING ALL TUBES IS A WASTE OF TIME AND MONEY. I ONLY REPLACE TUBES THAT ARE PROVEN BAD AFTER RECAPPING THE SET.
A TUBE THAT FAILS IN ONE SET MAY WORK PROPERLY IN ANOTHER.
YOU CAN SUBSTITUTE TUBES IF YOU HAVE A SUBSTITUTION BOOK. SUBBING TUBES IS NOT UNCOMMON.
I TEST ALL TUBES WITH A TUBE TESTER. IF A TUBE HAS HEATER/CATHODE LEAKAGE, I TOSS IT AND REPLACE IT.
IF THE EMISSION IS LOW, I REPLACE IT BUT DON'T TOSS THE OLD ONE. IT MAY STILL WORK SOMEWHERE.
DIRTY TUBES WORK AS WELL AS CLEAN ONES. CLEANING THE TUBES WITH GLASS CLEANER OR WATER WILL WIPE THE NUMBERS RIGHT OFF.
MOST TUBES ARE CHEAP AND READILY AVAILABLE. SWEEP TUBES (6KD6, 6JS6, 6LQ6) ARE GETTING EXPENSIVE. I WOULD SUGGEST KEEPING TUBES AVAILABLE AT ALL TIMES.
TUBES ARE IN A VACUUM AND DO NOT DETERIORATE FROM LACK OF USE.
IF A TUBE GLOWS BLUE, IT'S GASSY AND MUST BE REPLACED.
IF A TUBE GLOWS RED, THERE IS SOMETHING WRONG. NEVER LET A TUBE GLOW RED. IF IT HAPPENS, POWER DOWN IMMEDIATELY.
TUBES ARE A GOOD THING.
TUBES CAN DEVELOP SHORTS. IF YOU SUSPECT A SHORT, CHANGE IT AND SEE WHAT HAPPENS. IF THE SYMPTOM DISAPPEARS, THE TUBE YOU YANKED NEEDS TOSSED.
YOU NEED TO CLEAN ALL TUBE SOCKETS WITH CONTACT CLEANER. YOU CAN ALSO CLEAN THE TUBE'S PINS WITH THE CONTACT CLEANER.
PINS ON OCTAL TYPES CAN BE RESOLDERED IF YOU SUSPECT BAD CONNECTIONS. THIS IS NOT UNCOMMON.
IF THE BASE ON AN OCTAL TYPE IS LOOSE, YOU CAN REGLUE IT WITH SUPERGLUE.
THE ODDBALL TYPE IN YOUR SET WILL ALWAYS BE BAD AND YOU WON'T HAVE A REPLACEMENT IN YOUR JUNK BOX.
THERE ARE SEVERAL ONLINE SOURCES FOR TUBES. I WILL POST SOME OF THEM ON THE LINKS PAGE.