So I pulled my vacuum manifold from behind the glove box today and tested my Bellow lines...
Line 2 (Straight Red) is my fail...
I also found the connection for the Grey line... It appears to be a rubber hose that the Grey line feeds into. I hooked it up and all my flaps bar the center vents work again! And the buzzing from my boot is gone.
So I have one failed bellow at the center flap.
Seen as I have to remove the dash to replace the heater core pipes anyway now I think ill replace all the bellows....
How many are there?