Smack the carb with the handle of a screwdriver.
The only trick is doing it hard enough but not too hard, dont want to break anything.
If you are worried about the needle length you could undo the pilot screw and turn the primer face anti clockwise. So the arrow on the bottom is more at 1130 or 11 o'clock. Test it like that and see if it leaks.
Cheers, Bob.