Based on the fact that you show power output on AM and FM, you have proved most of the transmitter circuitry is good, almost certainly everything northwest and south of the balanced mixer on your schematic. You have also proved the PTT control circuitry.

Examine the schematic and do some elementary signal tracing east of the balanced mixer. I'm betting on the microphone itself, or the signal processing just west of it on your schematic.

The Man in the Maze
QRL at Baboquivari Peak, AZ