Jack, your finger is looking MUCH better.... whew!

Mathew, as you probably know, ST says you can lean the midrange by rotating the spraybar a bit -- fuel nipple towards the engne mounting lug. On my G90 I finally put a different brand of carb on it and it cured all. If you have an OS 46 carb, try putting it on your ST engine. (most 40 size engines have the same size opening)

Ernie