Hi Dude
Have a look at this thread to improve the audio quality.
on the subject of the 1 up button i have a couple of questions:
will it work if you sort the 1up terminal to the gnd terminal ( that the one that looks like a Christmas tree) try using a wire touching the inside of the screw terminal the screws at the top don’t always give a good electrical connection
the other thing to try would be to use different wires on the loom to connect to that terminal just to see of there is any fault connection within the loom.