The 7-year-old New West Symphony, which calls an LA suburb home, has an unusual problem – one fanned by its success. The orchestra has a budget of $2 million, and has run every year in the black. Its musicians are part-timers, professionals who for the most part make their livings playing in LA’s recording studios. The problem? If the orchestra gets bigger, it’ll lose its part-timers, and the quality of the players might decline. And yet, there is pressure to grow…