I apologize if this is a dumb question or has been answered some where else. I have a Craftsman lawn tractor still under warranty. If one of my rear tires gets no traction it will get all the power and spin like mad, but the side with traction won't move at all. Is this normal? I have tested this by jacking up my mower and stopping one tire with my finger (doesn't take much) the other tire spins like crazy. With my older mowers both rear tires got the same amount of power all the time. I am also having a heck of a time backing up with my tow behind cart (a 12 cubic foot model), much worse than I've experienced with my previous mowers. Thanks for any help.