“All four of Kent Nagano’s first concerts with the Montreal Symphony since he accepted his new job were sold out, and the overwhelming consensus was that the 53-year-old American has what it takes to revive the OSM’s artistic fortunes. He launched a new composition prize, charmed the public with interviews and comments from the stage, and helped the orchestra sound at least as good as it did during its glory years with Charles Dutoit.” But a bitter contract negotiation with musicians is a black cloud…