Jurors in San Francisco reported they were unable to reach a verdict on a millionaire landlord charged with plotting a bouquet bomb attack on his estranged wife. But U.S. District Judge Robert Schnacke sent them back to try again, noting they were only in their third day of deliberations. Peter Pilaski, 53, faces charges of placing a black-powder bomb in a bouquet of dried flowers that was delivered to his wife, Melanie, 42, in a federal office building in San Francisco in November, 1986. Mrs. Pilaski, who had filed for divorce, and a co-worker suffered cuts and burns when the bomb exploded. Shaun Small, 28, an apartment manager for Pilaski and reportedly his homosexual lover, was convicted in July of knowingly delivering the bomb and was sentenced to 15 years in prison.