If your goal is to repair your radio, I would short circuit your signal tracing a moment and try to decide what else might be wrong. Does the display work correctly? Do you hear any signals on your antenna. Does the same antenna pick up signals well with your other radio.
I would look at the connectors. Particularly the 8 pin audio connector. at the front of the board. I have had connection issues with it. Can you flick that harness while listening and introduce microphony. Before I got my last radio working I had to remove the wire from each port on the connector and tighten them up. The V4 board does not have a strong audio.
If your goal is to learn how to use your signal tracer it might pay to start on something that is working.
73
Dave
k0mbt
_Dave_ AD0B