Lowes just delivered a brand new John Deere D170 lawn tractor. It cranks but will not start. I read the manual thoroughly and am sure that I have the proper gas and oil levels. I checked the bypass rod and it is pushed firmly in to operating position. I sat firmly in the driver's seat. I set and locked the brake. It cranks with vigor, but will not start with throttle set all the way to choke. Any suggestions?