Hi.
I'd say there's more than one cause to these symptoms.
IME faint distortion on certain notes is almost always the result of an air leak or loose cab panels/braces. The grille and/or the ports and the badges can also produce all sorts of rattles.
As for the sound partially cutting out that can be remedied with a "jolt" over and over again, sounds a lot like a magnet fragment or other ferromagnetic debris in the air gap. That used to be pretty common on mishandled ceramic magnet drivers, I don't have enough experience about NEO's to say how likely it is with the different motor design.
Do rule out the cold solder joints and other wiring problems first though. Much cheaper.
IMHO, with 4 nights a week for 2+ years, the cab has probably paid itself by now... even with the NEO price hike

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Regards
Sam