"Top Gun" had been the No. 1 rental cassette for nearly all its eight weeks on the Billboard magazine rental chart. But it has finally been blasted out of the top spot, by "Ferris Bueller's Day Off." "Top Gun" slipped to third, behind "Ferris Bueller" and "Stand By Me," a consistent Top Five rental for most of its six-week chart life. "Peggy Sue Got Married" is the hot new rental, climbing to No. 12 in its second week on the chart. "Blue Velvet" (No. 6) and "Soul Man" (No. 7) continue to do well. "Top Gun" is still No. 1 on the sales chart. Other chart action: "Sleeping Beauty" is kidvid leader; "Bon Jovi" is the best-selling music cassette; and Bob Mann's "Automatic Golf" heads the how-to chart.