Thanks for the comments.
Have stripped it down and it’s sitting in a bath of engine degreaser hopefully a night in that then flushed with hot water will sort it out.
Will also get myself a can of compressed air and brake cleaner to blast though all the channels and holes as suggested.
Not sure what else more I can do other than ultra sonic bath.
How clean does the main jet and emulsion tube need to be? Do you have to scrape the holes and mating surfaces completely clean? They kind of get a build up off dark / grey gunge on them which I can scrape off with my nail.
Thanks for all the help.