Pull the dust cover from the flywheel and inspect the ring gear teeth, then have someone engage the starter while you watch from below with a bright light. It's a lot more effective to do it that way than to pull the starter, because you can see the relationship of both gears while the starter is running.
Stovebolt engines have a habit of stopping in one of three places when they're shut off, due to cylinders coming up on compression as they coast to a stop. Those three areas of the flywheel ring gear will wear more than other spots. Also look for wear in the stomp start linkage that allows the starter to begin turning before the starter drive pinion gear is fully engaged into the flywheel.
Jerry
