I have a kayfun Lite Plus clone by Tobeco and was thinking about changing the air adjustment screw with a slotted or Philips headed screw instead of the allen wrench one on it. Anyone know what size it is as I have no way of measuring it. I have a bag of the coil screws but only one in it for the air flow adjustment. Being so small I'm afraid I might loose it or screw up the head on it. Thanks for any input on the size of it.