Hi all.. time for a little update;

The game is now 100% working, after repairing the sound board and the auxiliary driver board.

The sound board i ended up replacing just about every IC on there to get it going as it had several problems. The main problem ICs ended up being U1, U4, U5 and U9... as well as R21 and C16 which are the timing components for the 555 timer IC on the board.
Part of U1 is the main oscillator for the tone generator, which wasnt working at all (no oscillation so no tones), U4 and U5 were causing the tones being played to be all over the place, and U9 was causing low volume. I socketed most of the ICs that i replaced, for easy repair in the future if needed.

For the auxiliary driver board i replaced U2 and U3 (both 4555 CMOS ICs) which saw the lights in the KISS lights for the BG working properly, plus resoldering a few header pins and replacing a burnt connector pin, in the pic the housing hasnt been replaced as yet but it will be soon, now that the game is all running properly.