I can't figure out the speed control adjustment on my 149. It either creeps to full blast or just falls into reverse at neutral. There appears to be minimal tension on the hydro lever. The problem is, I only have a c-clip on the shaft and no threads like the service manual shows. Also, the allen bolt and nut above I cannot get on either end. Every standard allen size doesn't work, maybe it was previously stripped, and the nut behind, I can't get any socket on. What should I do to get this Cub under control.