Mvs 6 slot only has sound on slot 1 neo geo

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Just picked up a Mvs 6 slot and it won't play sound on slot 2 3 4 5 6.
It plays sound on slot 1 and hardware test sound but if you choose another game the sound shuts off completely, slot 1 won't play sound and neither will hardware test until I power down the system.

If all games are removed and a game is put into slot 2 3 4 5 or 6 there is no sound at all. No intro sound or hardware test sound.

Only slot 1 plays sound and as soon as another game is browsed to all sound shits off till power cycle.

Slot 1 sound is perfect also, and ran for 2 hours fine.

Any ideas??