Here is a link to a video covering RCA push buttons. I believe you have the model A 39, not just 39
There are three wires that MUST be connected,to the push button assembly and they come from the chassis to the push buttons.I believe the video covers that. Make sure that the antenna is connected
One of the push buttons is for phono, and you should be able to see the RCA jack on the push buttons
Dan in Calgary.