The Tampa-based Florida Orchestra is battling the tide of red ink that has swamped so many American ensembles in recent years, and to hear orchestra officials tell it, the group is on the comeback trail, following a difficult season in which the musicians were forced to reopen their contract early and accept a pay cut. But with one of the orchestra’s key wind principals set to leave for the more financially secure San Diego Symphony, and rumors constantly swirling that music director Stefan Sanderling is being wooed by other ensembles, it’s proving difficult for the organization to shake the taint of its recent troubles. Still, Sanderling insists that he’s in this fight for the long haul.