My craftsman riding mower has an automatic hydrostratic transmisssion and mows fine, but has started suddenly going into neutral and will freewheel until I reach a flat spot in the yard. Then if I push the level all the way forward it will go, but will not go into reverse and still freewheels on a grade. Then all of a sudden it will work fine again. We have replaced the drive belt, check the fluid in the transmission, remove the rear wheels to check the key.
