Starter Issue, Starter does not respond to ignition switch Options

[downrange]

Restoring 1974 914 1.8 liter L Jetronic. No starter response to ignition switch. Replaced original starter - no luck. Installed Bosch Starter Relay Hot Start Kit - No luck. Cleaned ground connections to transmission ground strap - no luck. Any suggestions?

If not obvious, I am like a monkey with a iPhone when it comes to auto electronics.

[downrange]

The starter spins when jumped but does not crank engine. Attached is a picture of starter connections.

[GregAmy]

The spade terminal, when energized, pulls up the solenoid and engages the "bendix". When it is fully pulled up, the bendix connects power between the two big lugs on the solenoid, allowing the starter to spin.

For a functional starter to engage and spin the engine, power has to be put to both the solenoid lug and to the spade terminal.

To test the starter, you can jump across the terminal where the battery wire is connected to the yellow wire spade. If that is only spinning the starter but not engaging the flywheel then you likely have a bad solenoid (or, less likely a bad solenoid gear and/or flywheel, both of which can be inspected with the starter removed).

If you just jump across the big lug terminals then the starter will not engage the flywheel and will only spin.