KNOWN AFFECTIONATELY as Jonny Z, Jon Zazula has died of an auto-immune disease just 13 months after losing his wife and business partner Marsha. Metallica led the tributes to the 69-year-old who, along with Marsha, changed the face of heavy music by signing Metallica to their independent label Megaforce Records in 1982. Blown away by the band’s demo No Life ’Til Leather, the Zazulas – who owned a record shop called Rock ‘N’ Roll Heaven in New Jersey – put their money where their mouths were, borrowing cash to form their own label, and releasing the band’s thrash-metal classic Kill ’Em All the following year.