(a)where, after the transfer to the transferee of the property referred to in that sub-section but before the vesting of the property in the Central Government, the property has been damaged (otherwise than as a result of normal wear and tear), the compensation payable under that sub-section shall be reduced by such amount as the competent authority and the persons entitled to the compensation may agree within fifteen days of the vesting of the property in the Central Government or in default of such agreement as the Court may, on a reference made to it in this behalf by the competent authority or by any person duly authorised for the purpose by the competent authority, determine to be the amount that may have to be expended for restoring the property to the condition in which it was at the time of such transfer;