I'm glad you have managed to write this one up Paul. It is quite a fiddly one to do and diffficult to illustrate. It is possible to do with removing the bellows but as the venturi will always benefit from a gentle clean it is worth doing at the same time.
If the manifold support bracket is removed do make sure it is refitted tightly. I have had several instances over the years of the bolts coming out and then the manifold coming loose causing all sorts of running problems due to air leaks.
Mike
Original thread here.