I just noticed tilling the garden my 4WD is not working any longer on my Grand L3240 HST 3. Rear wheels turn but not front wheels. I dont know when this happened. I dont remember hearing anything bust. A friend who also owned a L3240 said it happened once to him and a wire came loose underneath from going over brush. I got underneath and didn't see any wires that could be the culprit. Any thoughts or ideals? I am trying to figure out if it electrical or mechanical and go from there.