the annual Encores! Off-Center summer season kicks off with a newly re-conceptualized, site-specific production of Stephen Schwartz’s 1978 flop “Working” that interpolates a series of new monologues based on interviews with facilities staff at New York City Center; an admirable concept that makes for a touching tribute to these workers, the effect blunts the power of the show and cuts short its escalating emotional resonance.  A suite of uneven performances and an oversized venue also hamper the effort.