I had a similar issue on my Fuji Roubaix. LBS said "it's shot, man. you have to replace it." I decided to go back to the other not so LBS where I got the bike from: "oh, it's probably just lose. You know, installation from the factory." He had his apprentice pop it out, clean it, reinstall it, retighten it. It works better than ever now. Get a second opinion before replacing it.