I have not gotten to the point of putting mine back in but have researched the leak issue. Make sure to use a good weather stripping glue in the groove, put the rubber in place and close the vent until it is dry. This should give a better seal than peal and stick. That makes sure you are sealed at the bottom. Next it has been suggested that you run a bead of caulk or silicon under the vent edge and smooth it down with your finger to a thin coat. This should give a good seal at the top. Like I said I haven't gotten there yet and it may not work but it sounds like from other post on this site and others that this will give you your best shot as keeping dry.
Let me know how it goes.
