Hi....first post...usually just glean the knowledge of the forum members
I have used two of the zoomzoom carbs, I'm prerty sure I mist have read about that issue here... anyways, you should uses the bracket from the stock carb, two screws holding the bracket, plus the spring return bracket has a nut holding it on and you have to move the assembly aside to get to one of the screws.
Not real easy to get the spring back in, but I've swapped them around a couple of times.
The carb works well enough that I just ordered another one for dub #2. But be sure to use the inline filter that comes with it ( or a filter of better quality)
I hope this helps some.