Starter question

When you jump the "big" terminals that does not test the solenoid. If you want an end to end bench test, you must ground the starter to the batter, and hook power to the top big terminal. Then jump power from the battery to the small terminal

And there's more to it. People often blame a solenoid when the starter is at fault, (not in this case) because of the "pull in winding" which is a trick

The solenoid actually has TWO separate windings: A large heavy "pull in" winding and a smaller "hold in winding."

The pull in winding draws a LOT of current and is designed to really snap the bendix into position as well as engage the contactor without sparking and arcing. THAT winding is connected from the solenoid start terminal to the STARTER MOTOR terminal (the bottom large terminal.) This puts that pull in winding IN SERIES with the motor and that means when the contactor pulls in, the pull in winding is then disconnected

After that, the "hold in" winding is the only one holding the starter in operation. This is a smaller, lighter winding which goes from the solenoid "start" terminal to ground

The point is, you must engage the small "start" terminal to be able to judge whether the bendix is being fully extended.