Recently picked up a 96 trailboss. It runs great and all, but only when choke half on. Can't get the choke setting to "full on" to stay in position, so know this needs adjusting first of all. As it runs and idled good while half choked, as soon as I turn choke off, it will no longer idle. My daughter has been riding it just fine while choke is half on, but it bugs me that it doesn't run right with Choke off. How do I adjust?