What homer52 said.
I recently rebuilt a Carter YF 2100S and it runs beautifully. Took me about 3 weeks to rebuild because it was so gummed up and stuck. I really studied on it, and there are a number of passages that meet internally around the idle screw. I had to slowly dig them out using a drill bit (not in a drill, with my fingers)
I would work at it, soak it, clean it blow it out and repeat until I was sure that all the passages everywhere were free. Sometimes you have to hold you finger over one to get it to blow out another as a passage might have three outlets.
Kurt
