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Is it #25 in the picture?
Yep, I have had to do this on a few of my teens!
It is very hard to find one "used" that is not starting to crack so if you decide to replace it look very close at where the shaft is welded to the plate! I would rebuild the whole assembly and at least check the throtle cable to make sure everything is smooth and clean.
Some times people put too heavy of a return spring than needed when they switch to carbs adding tension to the cable.