well any second hand vehicle that is sold is "sold as seen", unless you are a dealer, the buyer has absolutely no comeback. who knows what sort of abuse this scooter has suffered in the last ten days. tell the gentleman to open the yellow pages and find a local motorcycle mechanic to assist him with any further problems he may have. DO NOT offer to assist him in any way,including advising him on any repairs,as you could be held liable should any damage be caused due to your advice. point out that this is a used vehicle,sold in a private sale, and as such does not come with any guarantee.