V-Spec Carb
#2
It's fairly common. The idle screw area gets a burr. Pull the slide out and check for the burr. You may be able to get it out with a dental pick. If you see nothing, sand the edges of the idle screw slot in the slide with some 600 or finer grit sandpaper, then use some toothpaste and a clean cloth and polish the area. I polished the entire slide and the inside of the carb body. Clean up real good. Also, make sure that the slide is being pulled stright out of the carb body by the servo.