Seems like it should be the easiest thing in the world, but I'm ashamed
to admit I'm having trouble with this.

The replacement headphone plug has three gold-plated terminals, and the
headphone lead has three enamel-coated wires coming out: if the plug is
oriented in the 12 o'clock position I have red to right, green to left,
gold to the center pin.

I sand down the wires, tin them, and then do my best to solder them up,
but the holes in the terminals are very small and I don't see as well
these days.

Unfortunately even when I think I've got all three wires making a solid
electrical connection to the terminals, I'm often getting only one
channel, or intermittent contact, or wires shorting against each other
somehow.

Any suggestions to improve my game here?