I have the above chinese quad my father-n-law gave to my children earlier this year. It ran well when he purchased several years ago. Now I can get it to run but does not stay running. I have cleaned the carb and made sure all jets/ports are not clogged. I would like to replace with a new one. How do I know what brand to purchase. Are there markings on the carb to look for? and where is the best place to purchase? Thanks, Nelson