I too have suffered sore-shoulder-syndrome with a nearly new 6 hp Sears mower owned by a friend. It took a while to figure it out but it's a 2 pull process now. It was due to lack of fuel, so to speak. I don't know if the prime assembly has a leak or what but it doesn't work with "2-3" pumps-period. Try ignoring the admonition about not priming more than 2-3 pumps. I give it a brisk 25 and it has started on the second pull for the last 3 years.