You can loctite the screw if you wish but don't use anything on the moving parts, you need friction to make it work to throw the pawls out when you pull on the starter.
Agreed, the throttle plate and associated bits are cheap and flimsy, on an otherwise decent engine, which have a tendency to contort and bend out of shape after a few months of use. Unfortunately there is no easy fix for this, just bend it all back into shape.
