How can I fix the ariel?

Our sky box went on the blink, up until then, we had sky in all rooms and also normal telly in all rooms.

We simply changed the sky box - we still have sky in all rooms, main room is excellent but other rooms reception not great and we still have normal telly in all rooms but this reception is terrible. We did not retune anything, did not alter ariel just simply plugged in the new box?

What do we need to do to improve the pictures in all other rooms.