KM 5 Sound problem

I am working on a friends KM5 and the problem it is having is that every other key, including the black keys, doesn't produce the correct sound.

I have already pulled the battery to reset and uploaded patches to no avail. It is running Firmware 1.1 and I have no way to burn a new chip to try 1.2 but could that be the problem or should I try the resoldering of the solder joints and where would I look on the board for that particular problem? 

Thanks for your help.

Shane



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