In my opinion, ( I don't have the manual) the swash plate will not be directly connected to the pedals in that size of tractor. So you don't have a direct mechanical connection to the swash plate. It will be controlled by a hydraulic circuit. This on some tractors is electrically controlled sensing the position of the pedal and controlling the swash plate hydraulically. I am talking out of my hat as I don't have the manual for this rig, but this is what I think. Of course if the swash plate doesn't move in the opposite direction the slippers will not develop any pressure into the block ports and the pump wont pump fluid towards the hydraulic motor in that direction. The swash plate must change angle from neutral each direction. Of course the range selector is just a manual "crash box" transmission, and since it moves in reverse that is not the problem. The swash plate is not changing angle, for some reason, that is the problem.