On the right side connection are made via a small printed circuit board. Remove 2 screws in order to remove this for re-soldering or replacement of any of the wires.

On replacing this circuit board, take care to ensure that it's both the right way round and the right way up

If you are replacing the main lead with the jack plug on the end, make sure that you have suitable strain relief to prevent the lead pulling on the soldered connections.

The wire colours are:

Right: Red

Left: Green

Common (Ground): Gold.