 ", Osbourne was fired on 27 April 1979, due to his reliance on alcohol and drugs, and his reluctance to work on a new album.Osbourne was replaced by former Rainbow vocalist Ronnie James Dio in June 1979.Butler chose to leave shortly after his arrival, with Geoff Nicholls taking his place in mid-July before Dio's former bandmate Craig Gruber joined and Nicholls moved to keyboards and guitar.