Hi Mark. I’ve been going through the starter system on my engine, and have kind of figured it out.
Is there any life at all when you push the button.
A) Check the voltage going to the starter, either at the plug, or at the screw/blade on top of the starter when you press the button.
If power is getting to the starter, and its not spinning – then the harness and switch are fine.
B) Take the starter out. See if you can spins it by hand.
If it does not spin by hand, then the bearing is broken, or a magnet has come out inside the starter and jammed it up. You need a new starter.
C) Next apply power directly to the starter from a battery – positive to blade, negative to body of starter.
Does the motor start and spin? If is does not, then you need new brushes. Or your armature is shot.
D) Going back to A). If no power is getting to the starter, then most likey you have an intermittent break in your harness somewhere. A pin or connector in a plug might be loose, corroded, etc. Inspect it all closely. Play with and twist connectors and wires to see if it comes alive.
A weak battery will still make noise from the starter, and a ping or single crank from the engine, but it wont catch as there is not enough power to spin the bendix enough.
If it pings, try hooking a car battery to the system with jumper cable. That will have enough cranking power. If the engine starts, then you have a weak battery with not enough current.
E) Take out the bendix gear reducer. Clean it in gas. Many times. Also clean out the space it lives in. DO NOT LUBE IT. Dry it with air. See if it spins. Oil can coagulate and jam it up, and prevent it from reaching the flywheel.
In my case, it was many things – broken magnet inside starter, broken brushes, AND a bad bendix. I’m now waiting for a replacement bendix.
Stator is for charging the battery, so not relevant here. Coil is for firing the spark, so not relevant here. Both these parts have nothing to do with spinning the engine for starting.