It probably isn't the vent that's loose, it's the rivet that holds it on. You <span class="ev_code_RED">might</span> be able to tighten the rivet by careful (very careful) application of a hammer and punch. No need to replace the vent - at worst, you could drill out the rivet and replace it with a bolt and nut. That's how you would have to attach a replacement vent, if you bought one.