1)
Three tests to bench test the solenoid, text and video … 2)
To test the pull-in coil:
Insert a deep socket part way into solenoid.
Connect battery -ve to the large short stud of the solenoid (normal output to starter motor).
Momentarily apply +12 volt jumper wire to the small terminal of the solenoid (normally from the starter relay).
The socket should pull in.
Leave it pulled in to test the hold-in coil.
To test the hold-in coil:
Move the battery -ve jumper from the large short stud to the solenoid case.
Apply +12 volts to the small terminal and leave it connected.
Try to pull the socket out of the solenoid.
The hold-in coil should resist your effort to pull the socket out while +12 volts is applied to the small terminal.
Remove the +12 volts from the small terminal.
The socket should slide easily back out of the solenoid.
To load test the high-current contact plate of the solenoid:
A headlight bulb works well for this.
Jumper from batt +ve to to +ve of light.
Jumper from large long stud to -ve of light.
Jumper from batt -ve to large short stud.
Manually push in the plunger.
The bulb should light up.
And here is the YouTube video: Bench Test Solenoid from IronHead Sportster