San Francisco Opera, which is looking to rebound from a nearly $4 million deficit in 2003, may be staring down the barrel of a strike by the company’s chorus, dancers, and production staff, an action which could cancel the SFO’s summer season. The company previously reached an agreement for a 5% pay cut with its orchestra musicians, and says that it cannot afford more than a 2% raise for the members of the chorus, who are paid less than the pit musicians and are not guaranteed work. But the union representing the chorus insists that the current arrangement is unfair, and wants the singers’ work weeks to be guaranteed, and for their salaries to be pegged to 90% of the orchestra’s scale.