Hey monkey, I have THE SAME problem!
I have had it for 3 years now and have
been meaning to fix it ever since.
Would you want know how I solved it?
well ...I did nothing, that's right, I just
secured the pin to the unbroken side
and put the carb back together, the
square shape of the bowls' wall leaves
it NO SPACE to move or get lose once
it's on, never had a problem; as long
as that pin is well secured to that one
unbroken arm seems to be enough
for the floater to work properly.
But just knowing it's broken
still annoys me though.
* I like dr1445's solution the best, it's an easy
do-it-at-home solution that could work.
However, if you can, weld it!
Good luck.