B6 damp footwell

[fsipassat]

I've been reading a few posts on this and other forums about B6 footwells getting damp. Mine suffers from this on the front left hand side. I know it was a problem that could be solved on the B5 but the battery/plenum/pollen filter is a different set up on the later model.
Did anyone ever get to the bottom of this? The leak isnt massive, i've checked the drains under the screen and had the arch liner out and all seems ok there.
Next thing to do is get the carpet up and have a poke around but if anyone has been here before then some pointers would be great.
Many thanks.