Very likely, over time, the needle seat in the carburetor's been eroded to the point that it no longer meters fuel properly. This is indicated by the fact that it's passing fuel with the needle scewed in much farther than normal. This happens because, over time, the needle may have been closed too firmly a time or two, or vibration has caused the needle to hit the seat, or both. You would likely see a shiny area on the pointy part of the needle. This inidcates where the needle has hit the seat.

The only 'cure' is a new carburetor body. Here are the stock numbers and list prices of the parts you asked about:

OSMG3511 25681100 CARB BODY 40B 40-46FX $21.99

These parts can be ordered through any hobby retailer who sells O.S. Max engines and accessories.