If you have a multimeter, check for 12v in the aerial plug. There are 3 wires, one is black which is ground, the other two, if I remember right, are pink and blue on a post ford like yours Murdo

I can't remember which way around it is now, but you should have a constant live 12v in one of them, and a switched live in the other. I [b]THINK[/b] the pink is the constant live, then the blue is live when the radio is switched on. If not, it's the other way around. This switched live trips a relay inside the aerial unit which reverses the direction of the motor (hence putting the aerial up). When you turn the radio off, the current stops, relay goes back, aerial goes down

If you haven't got a multimeter, you can use a 12v christmas bulb! Make sure it's 12v otherwise it will just blow, but put one leg of the bulb in the black pin on the car's connector, then put the other in one of the others. If it lights up, it's live

I reckon, if none of the aerials are working, it's probably the feed from the headunit (usually blue on the headunit) which isn't sending anything to the aerial.