The aerial is what picks up the signal - and as you say it has snapped off on your site radio - this is why the signal is weak. You're lucky to hear anything.
You can buy replacement aerials - Amazon sell them as will hobby electronic stores. Look at your own radio to understand how it fits on.
In the mean time use a piece of wire (any wire will do) about 700 mm long.
Good Luck..., March 2016
