crackling sound out of right speaker

Just to be super super certain, when you switched speaker cables, the amplifier and everything upstream from the amplifier, that was driving the R speaker was then driving the L speaker, and vice-versa. If that is correct, then what I and Brf and Al have said has to be the case. Al brought up the interesting possibility that the speaker cable was picking up something. That's kind of a "zebra", but possible. (In medical terms, a zebra is a very rare cause of a common symptom or finding.)

I have a feeling this is something very simple going on in the speaker, but it depends upon your experience and sense of adventure whether you can fix it yourself. My advice remains the same: get your dealer involved if you have someone local. Why not call the US B&W representatives, if you have no local help?

I'm going to try moving some power cables that may be causing RFI/EMI and see what happens. Assuming that doesn't work, I'll reach out to my local dealer and see what they can do.
Thanks for all the great information and suggestions.

I'm going to try moving some power cables that may be causing RFI/EMI and see what happens.

Also, try turning off any dimmer switches, fluorescent lights, or compact fluorescent lights that may be in the vicinity of the cable to the right speaker.

Lew -- thanks for mentioning about the medical meaning of "zebra." Hadn't known that previously.

Regards,
-- Al

I had something similar to your problem. I had 2 Dale Resistors replaced in the preamp. 5.00 for parts. 125.00 bench fee, 87.00 shipping. When I heard the static it could only be heard a low or no volume. The music was able to hide it. Hope this helps, best of luck.

Are you using jumper cables betwenn posts? If so, be sure the jumper's posts are tightly screwed down.