Hi Grumpy, have done as you suggested. Started engine without air filter/hose attached ran smoothly as we know, attached hose and airfilter, started stuffing around so i slowly started closing the choke. I was able to close choke half way before the engine started to run smoothly. The first photo is of carby and i will let you know what i did. [Linked Image]

There was a little metal cap if front of mixture screw so i carefully drilled it out. Did try adjusting screw to different settings, 1&1/2 turns, 2&1/4 turns but made no difference were i put it. At the moment it is out 3/4 of a turn, that is were it originally was. The next photo shows the governor linkage on carby , underneath it is a small metal base that is screwed on, would it be worth taking it off to see what is under it, as there are no springs under governor linkage as there are with other mowers, wondering if there might be one under it. Let me know what you think. [Linked Image]