right side hum on tape, not on radio

[wildknees]

i bought this box, and upon arrival, it plays great on radio, however the tape playback hums on the right side with no music coming through.
same thing with the headphones. radio fine, tape with right side hum and no music.
what is going on here?

 

[Fatdog]

It could be an ungrounded cable for the tape deck head - OR - maybe something as simple as a dirty record switch. Try pressing REC and then STOP alternating several times and see if the hum diminishes.