Contractor dropped off his helicopter( this is the machine concreters use to smooth over concrete) saying he wanted it serviced. I checked oil level,set throttle lever to slow ,so that clutch would not disengage and start the turning.i leaned over at machine,pulled the starter cord,and the damned thing started flat out .i felt a whack in the back which was the long handle of the machine,and had me running around in circles yelling out for someone to turn it off,as I was unable to because of the rotating force of the handle pushed against my back.turned out the lever was turned to slow,BUT...throttle shaft was jammed wide open
