carpin_ The hovercard feature has never been standardized (at least afaik, e.g. it's not a component in the old-fashioned sense), it usually consists of an endpoint that is queried with jQuery when a username is hovered. This is normally added by PS or your customization partners.
May I ask what exactly is missing, the entire hovercard or just parts of it?
My best guess without more details is, that some kind of error occurs in the endpoint because Klout is not working anymore, is it possible that you have still activated "Profile Plus" in your community?