I thought about writing Webra-Austria with this question, but I've written to them before with technical questions such as this, and the replies from them are vauge at best so I thought I would just try here first and see what you think.

I put together a picture of a cut-away view of how the carb works. Anyone who has taken a Dynamix apart before (up to removing the mixture tube from its cast aluminum adjusting arm) will know right away what I'm asking about. When this arm is taken off, the factory setting is lost.

The question is where should the milled V and the bleed hole be in relation to the side of the intake bore, and also its radial position with the throttle plate fully open? I guess all of that might be decided how the low end mixture goes, where the V groove runs out and it stops letting fuel in.

I can assume the very end of the large V should just be touching the side of the bore allowing the full V shape to show, but where should it point more towards? Pointing up would cause backpressure in the needle, straight out seems logical, but having the edge of the V might be more like it for getting the best fuel mist.

Looking closely at the drawing, the top edge of the milled slot is a straight line, which is indicating that the top face of the milled V shape is rotated to meet 90 degrees to the bore. I don't know how much to trust or what to go on with what is drawn in the diagram.

JP, would the position of this one on my Webra .91 help?

I has Webra T-4 with Dynamix carburator, the milled slot are placed to the hole who are entered in to the intake bore.

To test the mixture tube works: connect the silicone tube to carburator and blow through the milled slot with your mouth. If you feel the passage are more tight while the carburator are in idling position and vice versa means the mixture tube are in correct position.
If not, rotate the pin with milled slot to align with the hole who are in connection with intake bore.