1) Remove carb by twisting anticlockwise 25 degrees then pulling from motor. Unplug all hoses.
2) Disassemble carby and clean it.
3) Reassemble and away you go.
There are like 10 parts in the whole carby, it's super-simple. I setup a large clean bench expecting 30-60 parts all to be taken apart in order, cleaned and reassembled carefully. Whole job took an hour. There are two springs in it, both under the rear of the carby (where the air intake and throttle cable goes) and the small one goes under the diaphram and the big one goes above the diaphram. In case you can't figure that out
Hope this encourages someone to do it rather than paying a shop to do it...