OK, that's the "fast idle cam" which opens the throttle a little when the choke is applied. How about threading the hole to the next larger size, like 1/4-28 or 6MM X 1? You would need to do a little custom fabricating of the bolt or screw but you'd have a full thread to work with.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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