Channels bleeding into each other

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

I have though over my suggestion and it is not going to work the way I thought it would. So forget the trying to disconnect on input.With one out, say right. Turning the balance fully to right. EITHER if crosstalk or the balance just does not cut 100% will still allow some signal. So the test is of no use. Sorry. All it can do it let you know just how much is bleeding. At the speakers though. with source right out. If you get signal (sound) from RIGHT speaker ... that IS how much crosstalk is bleeding from one channel to other.

I agree, the balance control in the op's unit may not be designed to fully cut off the sound. All depends on the way the circuit is implemented.                         
One way to test is to disconnect one channel source. THEN see if the balance control cuts off fully since there IS no signal to that channel. If you still get signal, then yeah you have a lot of crosstalk. If no signal, then it is just the balance control is not designed to go to zero for each channel.And if it does not anyway.. No big deal. nearly all stereo components have some crosstalk. Costs a lot of money to make a diual mono crosstalk free component.

Technical term is "crosstalk." 

Turning the balance all the way to the left or right is not how to tell. :) The balance control is not meant to go all the way to off, but to give you a range of adjustment for recordings, hearing, and situations when equal loudness is not ideal. 

Crosstalk is usually very difficult to avoid it completely in stereo components. Even very good stereo components will not be perfectly free of crosstalk, and when measured may be -60 to -90 dB. 

Best,

E