Tube amp down, need guidance from the experienced


I listened to my McIntosh MC275 Mk.IV all day yesterday without issues, as usual. Today I turned it on and left the room. Didn't pay attention at startup. Ten minutes later I realized it was not on. Eventually I figured the fuse had been blown, and replaced it. Turned it on again and found one KT88 was not glowing and cold. The rest of the tubes, both small signal tubes and KT88, were all on. Didn't attempt to play anything, turned it off, and here I am.

Obviously I need to replace the KT88, preferrably all of them. Unfortunately I don't have any spares on hand. What I'm anxious about, though, is to figure out if anything else was damaged. Is there reason to believe something else might have been damaged when this tube went off? First time a tube fails for me, and have seen a number of horror stories told on the net.

Thanks much!
lewinskih01
5 to 6000 hours on the tubes???? Wow. Who told you that the tubes have a useful life that long? I think you really were pushing your luck. Manufacturers will give an estimated life range for the tubes they use and will include a "fudge factor" amount of time, for the people that are too stuburn (not you) to get up and go get tubes replaced. But, I think you really went over the edge on your tubes. Once you get this taken care of, you should really pay attention to the manufacturers recommendations. Also, Ralph (Atmasphere's) advice is spot on.
OK, lesson learned: power tubes should be replaced after 2000 hours or so. How about signal tubes, like the 12AT7, 12AU, 12AX, 6922, be it them in the amp or pre amp?

I have no music but sort of feeling lucky it only seems the tube went bad.

Thanks all!
Small tubes can last 5000 or more hours. I replace mine when the sound becomes dull or noisy. I keep extras about so when I question the effects of age I simply substitute in a new tube(s) and see if there is a meaningful improvement.
Thank you.

Opinions re what KT88 to buy? Psvane black bottle, Genelec (Jim McShane recommended this one), other? Don't want to spend over $400.