Britax sunroof seals

My GLS has developed a nasty leak from the Britax pop-up sunroof.  I haven't had opportunity to work out where the water is coming in from yet but I'm guessing the rubber has compressed over the years and recent cleaning of the seal and application of a bit of rubber grease looks like its only made matters worse.  So could anyone point me in the direction of where I might get a new seal for the sunroof or has some pictures of how the thing fits together? The britax web site just has kiddie seats on it and they don't look like they do roof anymore.   Cheers in advance.

Richard