I have a working frogger with no sound. It started with a loud buzz/hum, so I changed the sound amp(M51516L). That cleared the loud buzz and the volume control is known to work. The board in this frogger is 834-0069. The top board(the one with the amp) has been swapped with a known good board and that fixed the sound. What would be the next step in the troubleshooting approach? Any help would be appreciated.

