Thanks HighPlains,

I have servo hum at any trim setting less than half but at half there is zero opening on the barrel.

I just checked it out again, it appears that servo was never meant to be at low throttle with trim bottomed out,

that's what was binding it. At full up trim I have almost the 1/16 inch opening but at full throttle its not full open.

After I adjust the carb linkage out it should be fine. I may rotate that horn too.

Thanks!