Hi @spyhill ,
Before you pull it apart, check that it is not the wiring at the cable plug end that is the problem.
The left speaker wire is connected to the "tip" connector of the plug.
Plug in your earphones to an audio source and gently flex the cable, back and forth directly where it leaves the plug to listen if the left speaker audio comes and goes. Wear the headphones on the left ear only to aid the process of listening for the audio.
If the audio does come and go then either the wire in the cable has fractured at that point or it may be a faulty connection in the plug itself.
If so you'll have to cut the cable and rewire the plug, with a new plug (it's easier this way).
Apologies if you've tried this already.