Although this thread looks like it's nearly two years old, with the problem fixed, I'll respond anyway. The 1965 and 66 Thunderbird AM/FM radios have flipover buttons. Depending on whether the red line is at the top or bottom, that button will select an AM or an FM station. The 65 set is known for these buttons getting rather sloppy, to the point where you have to press several times or jiggle/twist the button itself to get the switch to jump between bands. The 66 is redesigned and better, but can still do it.
The biggest cause of this is the button shaft actually getting bent. If you look closely, each button has two shafts -- the metal shaft that the button is mounted on, and the shaft that actually depresses and pushes against the treadle. Those shafts should be sliding against each other, but you might notice that the shaft holding the button is bent to the point where there is a gap between it and the other shaft. In other words the button itself sits physically to the left of where it should be. You can press the button to where it pushes the switch to the left, and it works fine, but flip it so it will push it to the right, and it doesn't seem to go far enough.
I get these radios on the bench all the time. In fact I have a 65 radio (converted to stereo) in my own 64 -- don't tell anyone. There's a trick to this; it takes a little practice. I start by pulling the button out, as if to set a station. Then with long nose pliers I bend the shaft, right where it meets the second shaft. Holding it in place, I take another pair of long nose pliers and bend the shaft back, closer to the button itself. Ultimately the shaft needs to be straightened out, then straight near the button, and of course the button itself needs to be straight. Keep working it, a little at a time, and it will fall into place. When everything is straight that button will flip the switch in both directions. Repeat for the other 4 presets.
There's a fly in the soup. While doing this it may be possible to bend that rear shaft. If that happens the button may stick in the inserted position and not pop back out. Yes you can reach it from underneath with the bottom cover removed. Again it's a matter of playing with it. Once everything is lined up, the button will push easily, release quickly, and will flip the switch in both directions.
