When I said running really well I failed to mention the mid-range running was still questionable. I should have been clearer when describing my findings. Full speed and idle were both pretty good.
Would you be able to post an example of progression holes and a single idle discharge port as I am not familiar with these terms? I will however check this out tonight and try to get a photo for the forum.
The idle mixture screw is currently sitting about half way. I.e. half way between being fully screwed out or fully screwed in. I hope that makes sense. Turning the adjustment screw anti clockwise didn�t make much of a difference to the mid-range running when I gave it a try.
I am quite confident that I have covered all bases in regard to an air leak without splitting the crankcase and resealing it which I image would be a similar process to splitting the crankcase on a full crank Victa 2 stroke engine.