There may be one or two readers who may not realise the following, I didn't :-
When I bought an A10 RGS rep to rebuild and make a better job of it, on taking the 389 carb off I noticed that at the top of the carb where the air control cable comes into the top cap the cable and cable end ferrule were really distorted. I made a mental note to take a closer look on reassembly. What I discovered was that the air control cable passed through an adjuster, just like the throttle cable and as a result due to very restricted room below the frame top tube, the cable had to be distorted to fit. When I checked the Amal reference book I picked up at Shepton Mallet last week, I discovered that there should not be an air cable adjuster at the top of the carb and the cable should fit directly into a ferrule, part no.6/132a, which gives a lot more room for the cable run. Failure to do this can of course restrict the cable wire's movement and hence the action of the choke slide in the carb. According to the Amal book, this applies to A10s in general.
I also found a small approx. 1/4" long spacer under the air slide spring, in the spring slot of the air slide, presumably to increase the spring force to overcome the cable stiffness which, when I looked into the carb, prevented the choke from completely clearing the bore diameter with the lever fully open.
Hope this helps someone.
Alan