Leaky or opening condensers (the two terms are diametrically opposit to eachother) cause distortion and other strange audio problems. They can cause crackling and irratic operation. Failing volume controls (bass, treble, and volume) can also cause sound failures within the set. They don't usually cause distortion. Drifting resistors can cause distortion, weak power, and sometimes strange audio changes (low bass or treble). Usually condensers are your first problem.

If you are in fact having trouble with the set, then it is wise to replace dud tubes and then check under the set. Replacing all of the tubes won't likely solve anything, as tubes are not likely your problem in the first place.

I guess, instead of writing all of this, I should simply ask you if you are in fact having trouble with your set, or if you are simply trying to obtain maximum performance from the set by replacing all tubes. As all of our comments suggest, however, replacement of all tubes won't necessarily benefit you in any way.

For some people, especially beginner radio enthusiasts, it is hard to accept the fact that you might actually have to get inside the chassis and replace components. After several tube replacements, however, if you're actually having trouble, you'll find that under the chassis is often where the real trouble lies.

Thomas