So I tore down the engine for a rebuild and remove the starter. I never heard the starter crank so I decided that it would be a good idea to make sure the solenoid and starter were good.

Solenoid bad, starter good which leads to my question. The starter is a Bendix type starter where the starter gear is thrown out to engage the flywheel. What makes the starter gear go back in? On a static test, the gear comes out but doesn't go back in. I read somewhere that the engine running will throw it back it. Is that correct? Will it go back in by itself when the engine cranks?

My old Ford tractor has a Bendix type starter also and if it cranks and fires momentarily, it will cause the starter to disengage and just spin with the start switch pressed down, so I have to wait until the starter stops and the crank again.