To install - simply remove rear screw and pull out weatherstrip.  If they are secure well with glue you made need a narrow scraper, or flat blade screwdriver to help work them out as you pull on the gasket.  Once removed - clean out as much of the old glue and gasket chunks as you can.  To install - run a thin bead of flexible adhesive.  We like E-6000 because it is readily available at most big box stores or craft stores, 3M black weatherstrip adhesive obviously works well too.  Don't overdue the glue!  If properly installed the gasket should be mechanically held in place by the lips in the retainer channel.