[Mondial]

That's not a loose wire. Its a "gimmick" capacitor. It should be wrapped around the adjacent wire as it was in your original photo.

The unterminated wire provides a small amount of coupling capacitance across the antenna coil to increase sensitivity at the high end of the broadcast band. 

Before doing anything else, check the coils with an ohmmeter to make sure there are no open windings. Open windings in the ant or oscillator coils are probably the most common problems with this type radio.