This episode's headline: New Assault; Canada Divided; Raiders' Return; Muse of Morocco. The guests include SEN. DENNIS DeCONCINI, [D] Arizona; SEN. ORRIN HATCH, [R] Utah; Premier Clyde Wells, Newfoundland; CORRESPONDENTS: ROGER MUDD; ROBERT HONDA; ESSAYIST: AMEI WALLACH. Byline: In New York: ROBERT MacNeil; In Washington: JAMES LEHRER