Do you have the impression that the distortion is from the speaker
itself or an internal problem from the receiver itself? I really don't
know anything about the 390, so I'm just thinking in very basic terms
here. Natturally my first thought is a blown speaker, but you didn't
say if the audio is distorted while listening through your headphones.
If it is, guess it's not a speaker problem....sorry, I'm sounding like
my brother who is notorious for pointing out the obvious. If not a
speaker prob, then I'll then I'll just pray, cause I'm like Schultz on
Hogan Hero's....I know nothing. Good luck on the fix. I'd be
interested in what worked on your repairs/replacements. Take care.