A fire Saturday at NBC's New York headquarters didn't dissuade Democratic presidential hopeful Bruce Babbitt from keeping his rendezvous with ridicule on "Saturday Night Live." In a skit poking fun at the "character issue" of the presidential campaign, the former Arizona governor confessed that he often went through supermarkets' express lanes with more than 10 items in his basket. . . . On a related fire note, New York's WNBC-TV was knocked off the air for seven minutes but switched to an emergency broadcast facility. Instead of continuing with regular programming, however, the station aired an ancient John Wayne movie called "The Lucky Texan." The first half of the film aired without sound.