radio diagnosis

We have to gliders at our club with similar radio problems. Neither have the same setup/hardware.

Both can receive fine. When you press the Push To Talk button other radios hear the click, but no voice.

So what can we learn from this?

I don't know if this is more likely a microphone problem, a transmitter problem, could be the PTT button too, etc?

I didn't have a voltmeter to verify that the battery was strong enough, but can do that next time.

what should our next step be?

Chris