I know basic details about the ocean mod but won’t say anything since it seems he’s back in business.
The ocean mod was a special type of design that Aldrich himself named because he said the gain sounded like the ocean. Anytime I’ve heard a swirling flicker noise when not playing though, it has been a symptom of instability somewhere in the circuit and usually also accompanied by a bad preamp tube, but that’s a whole different topic.
I joined the forum to originally send not one but two Marshall’s to Mark to get his ocean mods. I’m glad I never did - as I was saving for his work right when everything bad was going down.
The preamp sounds great but it’s overpriced and probably gooped to hell and back, so good luck getting it repaired if it is.