There are two sound systems on a WW. One is operated by the sound board, and the other is the MPU sound section. It is my understanding that the music test will test the sound section on the sound board, and the sound test is for the MPU sound section.

You state that the music plays after the game, so I am assuming that the issue is with communication with the sound board. If that is the case, you need to look at U42 on the MPU. This chip is in the area that typically gets damaged by puking batteries. Outputs PA0 through PA7 are used to communicate with the sound board. On WW, these outputs go the plug J21, and the ribbon cable then goes to the Sound overlay board, and then to the Sound board.

Since you have acid damage, trace PA0 through PA7 from U42 to plug J21. Then check the ribbon cables. Make sure you have good continuity on all the cables between the boards.