Hi Jack,
First the good news, I have the idle speed down to what I think is about right. The instructions state to gently turn the spindle in a anti clockwise direction and tighten the throttle arm clamp, did this and still had full revs. Deafening ! Tried again and this time put some effort in and the spindle went further, from about 12 o'clock to 11 o'clock position. This bought the revs down to an almost idle which may be right for this model.
I would say that the Turner chassis is from the reworked Carter mould. I notice on the rear platform of mine that there is mould mark which I think blanks out the 18" cut lettering that is present on the Carter. The Made in Australia is left but the Automatic lettering is covered up by the step treads. I guess they did away with the Automatic wording as a manual model was also available? The 18" cut lettering as this was already incorporated as part of the Turner logo on the front.
Now that my base is a lot cleaner I will post a pic of the rear deck showing this.