Hi Paul, I have a '49 B with similar problems. It took me about 3 to 4 years to learn a trick that starts it every time. Set the throttle at 1/4 and do a one revolution choke. Stand beside the flywheel and twist the throttle back to off and then hit the starter. After it fires then let go of the throttle and the tractor usually springs to life. Wayne in Castle Rock, WA