Modern Vespa

In my Vespa PX-150 fuel tap (connected with the carburetor) when I tight with the screw with it, after 5 or 6 threads the screw doesn't tight properly . The threads of the carburetor are faulty which cause fuel leakage from that area and come down to the engine bottom side and drop drop fall in the floor . Please guide me that how may I tight the petrol screw with the carburetor properly the threads are free even i full tight it ? Please guide me.
A picture for understand is attached herewith.

Chase the carb threads with a bottoming tap? Use a shorter bolt?

The last thing you can do is to rebore the thread hole, then make a new bigger thread and use a bigger bolt, for example M8 bolt.

The threads may have been cross threaded. Inspect/change the gaskets or add an additional gasket to prevent the bolt from bottoming out.

Thanks all for the replies. Yes the options are good to apply. Well "xperimental21" if I rebore the thread hole what kind of tool may I use ?
" sp949 " About the gaskets, this means the to change/add additional (red tiny rings) close to thread hole ? Please elaborate it a little bit .
Thanks

Or you can replace the part
https://www.scootermercato.com/Scooter-Parts/Carb-Parts/132369

there is no place for M8 bolt

I think it is much batter to replace it with the new one .