also reseat the connectors on the cpu, there might be a bad connection on the cpu end.

are all the sounds that are working correct? or is it playing the wrong sounds?

this is what confuses me. the sounds that do work are correct and are consistant, and whilst the sound track that usually plays during the game currently isnt. all the other game plays sounds like bumper sounds, target sounds, all work perfectly,
the game will play the opening game starting song, but it wont play the finish song or music track during game play but will play bumper sounds and so on.

could you please point out which is the cpu, ill give that a try. cheers
edit had a think, the cpu is the entire board isnt it? the 4th pic is the cpu? i was looking for a cpu simular to pc lol, then i remembered cpu's werent that small in the 80's, lol