Thx for the info.
It has to be in the carby, i'll check it out again.
It looks a very simple set up, & has to be a block somewhere.
I have soaked it in petrol over night & have pocked a very fine copper wire down three tiny holes, all seems ok.
The main jet blasts air quite easily so have eliminated that.
I will try the online manual to see if it can enlighten me with some more info?
Thx again
