Andy
See if you have sidetone when using cw. If you don't have a key, you still need that external 4.7k resistor anyway. Then put a short across the key input to listen for sidetone audio. If none, possibly the audio amp ic is defective, a common v3 malady I am told. Also you can inject audio into its input to see if this is the issue.
If this is the problem, I would be so tempted to not repair it, but use another audio amp board. V3 folk can chime in, or search here for v3 audio.
Curt
