For the water leak, I do not have a V2 mast, but what I read on the FB group was that the connector part entering the mast is not flat like on the V1, so if it pushes the rubber blocks, it sets them at a slight angle, and they leak.
You have to push the blocks in yourself by hand with some rod, to be sure they sit straight and are not touched by the connector.
PS: it is a pity that a lot of this info happen on the Facebook group, where it is very difficult to find anything, and is not indexed by Google. An FB group was necessary I guess because a lot of people seem to not want to use a forum nowadays... I try to copy the info I find useful on the Gong forum (or here), but I miss some of them.
Edit: ah, here it is:
www.facebook.com/groups/174002002631963/permalink/4278301208868668/In French, but you can see the pic:
I guess filling the "U" of the connector to obtain a flat end could work, too.
Another example of "best is worse": trying to gain some grams by removing some material can have unexpected consequences :-)