A while ago I tracked down a leak in my drivers footwell to the plenum conduit box cover (I think thats what its called).

After running some sillicon round it the leak stopped.Ive had a few months of dry carpets until the other day when I noticed that the footwell was getting wet again.

I think its time to replace the cover in the hope that it comes with a new seal to stop the leak.

Has anyone ever replaced this item and how much of a job is it ?