What's the best way to break in a new drummer?     Take him with you on a high-profile television appearance.      Paul McCartney was coming off his World Tour, lost a drummer (was Paul a model for Spinal Tap?) and agreed to appear on MTV's new-ish television show (interesting performances, moderate audience) called "Unplugged".     This week we go back a little over thirty years to talk about the performances, the songs and see how well the TV special holds up for modern audiences.