I have a cub 1515 with a kohler 15hp. The mower disengages when going down hill. It has several safety shut offs. The ones that I know of are on the seat and a reverse shutoff. I unplugged the one on the seat and the mower still worked so i don't think that is the problem. I don't know where the other sensor is but I think it must be on the hydrostatic tran under the seat. Any suggestions of how to start trouble shooting would be greatly appreciated.