Very easy to test starter. If you want to avoid removing it. Which I don’t see why you would because it’s incredibly easy to do so. Take a set of jumper cables. Hook them to the battery and on starter end ground black cable anywhere on starter and as soon as positive touches the big terminal on starter solenoid. The starter should spin. If not the starter needs replaced or rebuilt with new brushes. Easy to do. If the solenoid clicks when turning the key. Solenoid is good and doing it’s job. It’s easier to test starter removed from car. But, You can do it either way.
