crackling sound out of right speaker

Lewn; I've done the following:
Changed speaker cables (tried different cables)
Switched Left and right speaker cables (the crackling moves from right to left)
Moved interconnects (right to left and vice versa)
Tried a different amp which didn't produce a crackling sound.
Replaced input tubes in preamp and amp.
Although I did notice that the crackling did become less after changing input tubes in the amp.

"Changed speaker cables (tried different cables)"
Result?...

"Switched Left and right speaker cables (the crackling moves from right to left)"
[Lew]Do you mean to say that you attached the R side of the amplifier to the L speaker and vice versa?...

"Moved interconnects (right to left and vice versa)" [Lew] Do you mean to say that the L side of the preamp was then driving the R amplifier? Result?...

"Tried a different amp which didn't produce a crackling sound."
[Lew] you do realize that some of these results, most notably the effect of swapping R to L and L to R amp/speaker combos, assuming you swapped one end of the speaker cables, are different from your original post that started this thread, and different from some of your additional posts that were in response to questions. However, if the latest info is valid, you may indeed have a problem in one channel of your amplifier. Did you ever try swapping the amplifier output tubes from one side of the amp to the other? If that didn't move the problem from one channel to the other, then you probably have a bad solder joint or a failing tube socket or some such thing.

This sounds like an eminently fixable problem that should not require the purchase of a new amplifier, but I realize that competent technical assistance is not readily available in most parts of the US these days. This is the world of "if it's broken, throw it away".

Have you swapped interconnect cables to preamp/source.

Lewm; agreed I believe it is fixable but quite frankly I'm a bit tired of messing around with it. I have had the amp in the shop and they said that nothing's wrong with it. I am sort of at my wits end with it, It's a great amp, considering the issues I've had and I don't plan to throw the amp away but to sell it with full disclosure what has been the issue and what has been done.

@Bevis yes I have changed interconnects as well.

I am as puzzled as you may be, but the fact remains that the amplifier may be blameless. Anyway, I understand your running out of patience in a case like this.