There is an oring that goes on the bottom of the carb slide, right below the hole that the main jet mounts in. I dont see this on the diagram.
A carb I was in today showed a little age on this oring, but was usable.. I have to imagine at some point one of these were bad on someone.. maybe there is no ill effect?
(http://i205.photobucket.com/albums/bb17/ben_2_go/Motorcycle%20Stuff/Mikuni%20BST33SS%20Carbs/slideguide4.jpg)
Just curious what the solution for that were if it were ever needed?