Nikki carb information

[Jumpinjacks]

Hi guys,
I have a nikki carb which I have just installed, and haven't really run it properly yet as I'm in the middle of doing a rock lobster for the sj.
I have noticed after leaving it stand for a couple of days that the fuel level has gone down in the float chamber and is leaking from the bottom of the carb where it attachs to the manifold. Has anyone got any idea what could cause this?
I take it the carb needs tightening more but still it shouldn't go from the float chamber.
When I tightened up the carb I had to bend a part to tighten the nut and now it seems to move freely up and down, the part I mean is 186 counter weight shaft in the following diagram: http://www.carbs.freeuk.com/nikki_image.htm" onclick="window.open(this.href);return false;
What does a counter weight shaft do?
Any help would be great