1997 Lexus ES 300 Fuel Leak in engine compartment from damp

1997 Lexus ES300. I have a gas leak (drip) coming from the fuel induction damper. The leak is intermittent and usually starts when the engine has been on for a while. Is it an easy removal/install ? I got the information on the part , but could it be a defective seal. The gas seems to drip from around the screw.
Thanks.[img:cf1e805c40]http://www.2carpros.com/forum/automotive_pictures/183131_IMAGE_015_1.jpg[/img:cf1e805c40]