UPDATE - my bike has gone in & should, by now, be in pieces. Hopefully, I'll have something to report by 11/11/11, an auspicious day!

Thanks Motokai & Eric. This is very helpful.

I have used injector cleaner once or twice, but not for at least 6 months. Hence, there might be some gumming up. I also noticed that the Beijing Service Center has a fancy-shmancy new injector cleaning machine, so perhaps it knows something us owners do not.

By the way, when I went to deliver my JH600 a few days ago, its battery was down (from lack of use) ... but it had just barely enough juice to start it. And the stalls were worse than ever - at least every 20 or 30 seconds. After riding around my parking lot, and having no less than a dozen stalls, I swapped the battery with my fully-charged "B" and my "A" returned to its more-normal acute stalling, allowing me to ride the bike over to the Service Center.