Thanks Grumpy. Unfortunately the Idle screw setup looks a bit different on this carb as this is a 'Rotary Valve' carb and does not have the usual butterfly setup.
I took the screw off anyway but there are no passages to clean as the needle goes directly into the main jet below
As a side task, I took the Walbro WYC-27 off my blower and fitted it to the trimmer. The results were impressive. The trimmer starts first go (even when it was new this machine did not start first go with Ruixing carb) and runs like a dream.
So after not being able to do achieve any kind of improvement I have ordered a genuine Walbro Carby from USA for around $45 which I think is better then stuffing around with rebuild kits that will not guarantee a good result.
Many thanks for all the help!
