This is a single lever control with only one button underneath the handle that is the neutral safety switch, preventing you from accidently engaging the throttle. Depressing the button puts the engine into gear. There appears to be no other button or manner of disengaging the prop in order to give it more gas like when you are warming up the engine. Not sure about the model, seems to be original equipment on this old boat! Any suggestions of what to do short of replacing it with a more modern throttle control?