That puts us back to bad pots. It does not clear the issue of two channels moving from one stick, but we are getting into an area we will have to focus on one issue at a time.
J4 being off center in hardware Monitor is almost certainly a "Bad Pot" issue. That one will benefit from either using contact cleaner on it, or securing a loose pot.
This is a great video for hyow to spray some contact cleaner on the pots without disassembling. It might be best to at least try this before securing the pots:
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