Thinking I’all redo all neck connections, take off, clean and redo, to see if that works.
I think that's a good direction. IMO, it might not be a bad idea to start over completely. Work through the diagram methodically, attaching each wire in a way like you are "seeing" the signal path through each component.

Also, I reckon you only need about 20% as much of the solder you currently have on there. With soldering, "more" is not "better".
With large globs of solder, you can create more problems rather than fix them. Too much solder can also mask problems.
It takes lots of practise to get good at it. I'm not an expert btw, but I've learnt by making mistakes and always improving.