Hi Jokeyman123, I checked your PX350 mod, really interesting stuff! I now see how it looks like inside it and it will be helpful when I'm gonna check the ribbons. Unfortunately, I don't have the tools to open it (moved to a new place), so I won't be able to check if a ribbon cable is not seated well for a while.
I just checked auto setting though, it was already off.
About the sustain jack connection, do you think it could be a possibility? Considering only changing the volume overrides the sustain value, but not the other way around (fortunately, if it was that would have been a nightmare). If this is it I guess I would definitely have to send it back somehow to get it fixed.
Thak you for all of those suggestions, I'm glad I was able to boggle your minds with that surprising feature!