I can't remember exactly how I got the carb off (it's been about three or four years.) I remember it was hard because I had to remove some of the throttle linkage. Getting the tank out of the way may also help. You may want to take a photo (or two) of the linkage before removing it so you know what it's supposed to look like.
If you have an air compressor you could try blowing air through any of the passages that you can get to without removing the carb.
I hope you don't give up easily -- it's a very good engine that's no longer available new.