The Seattle Symphony is approaching the two-year mark in its search for a new concertmaster, and orchestra higher-ups say they hope to have a new leader in place by the beginning of the 2006-07 season. For those who attend concerts at Benaroya Hall, the search process has been unusually easy to follow, with candidates regularly playing with the orchestra for a week or two, and a select few invited back for a second look. It’s all a far cry from the usual secretive audition process most orchestra musicians go through.