my tractor has the power reverser and it doesn't work forward or reverse and the 4 wheel drive light is on and no RPMs reguester. All the fuses and lights work. It starts just will not move. when I move the pto leaver just off the lock position the 4 wheel drive light goes out and the RPMs show up and it then moves and shifts normal. Of course the PTO light is on now and the pto is not turning because its not engaged . I wounder if I drive it this way if I will be rubbing on the pto clutch. Is there a book or page that shows where all the different sensers are and how to get to them. there is so much plastic and wires. How do you trouble shoot stuff like this.