DK you are looking at the wrong screw. Look at Jakas picture agine the one on the left, now find the throttle arm (that is where you hook up the pushrod from the throttle servo). Inside this throttle arm where it pivots is a hole and you can see inside this hole a tiny screw with a screwdriver slot. This is the mid range needle valve on a TT Pro and on the engines in Jaka's photos.

John