Sounds like you might be right with the starter. I would also check to make sure the carb and hoses aren't clogged. I used to work at Tractor Supply and we would have all kinds of things like generators, pumps and chainsaws come back with with clogged/maladjusted carbs. It was a real pain in the butt because the manager would rather send it off than let us fix them, not that it stopped us on a few cases.
