Many times vent caps can be damaged by lawn tools, animals, etc.  The Dundas Jafine EzFix Replacement Vent Cap and Gasket Kit can easily be installed over the existing vent cap cover.  It is very simple and an effective way to fix the problem and move on to bigger and better things.  You can watch the following video or visit the website at http://www.dundasjafine.com/products/11-replacement-caps/137-ezfix-replacement-vent-cap-and-gasket-kit.html#