Channels bleeding into each other


Hi, tried to research this but apparently was not asking the correct question. I have a Yamaha CR820 whose channels seen to be bleeding into the other. When I turn a channel to 0 to mute that channel sound from the other  channel seems to come through. Simple cleaning required or sound like a more serious problem? Any insights would be greatly appreciated. Thanks, Dave.
italian
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Erik and Elizabeth thank you both for your insights. I had purchased this a few years ago with the idea of having it restored, it’s actually in pretty nice shape for its age. I was fiddling around with it recently and came across the crosstalk. Will hook it up again and give it a re-listen. Again thanks much. Dave