all US carbs are thermowax element chokes - with some kind of electric connections to it. Geronimo's failed at 70K miles in 3 years - that's why he has had a Weber since 83. If you can determine which screw is for the choke adjustment, it should contact the cam that has teeth on it. When you rotate the carb throttle to full open when cold, you should see the linkage move the screw toward the cam when it returns to closed position.