Have you checked the governor valve for for equal clearance?
Hold the governor by the gear and let the body hang down.
Look inside and you will see some clearance at the land of the valve.
Now depress the counterweights.
The clearance at the other end of the valve should be equal or close to equal.
Have you ever switched governors and given it a try?
I am still interested in the correct geometry of the TV cable.
Something just rubs me about that. Did you try a minimum adjustment? As in leave it connected but back it right off.
I used to enjoy challenges like this but after so many the hair starts to disappear. I am nearly bald now.