How can you tell when tubes are shot?

WARNING WARNING WARNING

ignore previous post. ignore previous post.

Guess the girlfriend wasn't around Kubla?

Kubla must be an Army guy.....in the Air Force we were so
macho...we used "other" body parts to test electical
voltages....let alone keep the curl in our hair!

I think there's allot of good advice on the previous posts.
I might add that turning the epuipment on/off really is not a problem with the newer design ARC epuipment. I got tired of replacing tubes so I just plan out listening time to turn
everything on about an hour before. Keeping the system on also creates one other gremlin and that is that resisters/capacitors begin to dry out over a long period of
sustained use which presents degradations apart from the
tube issue alone. I tend to buy the highest quality I can
afford and then keep/tweek for along time. As such, I believe it's best to turn the epuipment on/off if there are
sustained periods of non-use.

I like Sugarbrie's take which is an easy way to tell. Another thing to watch out for (if you are not used to switching/comparing tubes) is to allow them to cool all the way down before handling/changing them. Not doing so can damage or take a lot of life away from them (especially non Russian 6922 types many of which are very frail). Another good practice is to clean the glass globes and pins (I use electrician's alcohal which is cheap) and use a clean piece of cotten to handle and install the tubes which will keep skins oils and such off of them.