Follow the choke cable down to the left carb. There is a plastic nut that links it to the carb. Disconnect it and you will see that it ends in a small cylinder with a needle, i.e., it's not a 'choke' but an enrichening valve. Do the left side because getting at the right is a real bitch while the left one is easy. It is the needle which gets hung up and you need to replace the cable to replace the needles. Again, I couldn't see anything wrong with eiter side, but replacing the cable fixed the problem. And, again, the mechanic who diagnosed the problem is one of the best I have ever met. He knew what it was instantly when I described the problem. That leads me to beleive it is not an unusual problem.