At first glance, I don't believe it's the starter.

I'd guess that it's low voltage......reason being battery, or alternator, or cables. When is the last time the cables were removed and cleaned?

Get a good set of jumper cables and see if another vehicle will allow the starter to easily rotate the engine and get it running. If so, then the starter is eliminated as the culprit. But, note that poor quality jumper cables, or a poor connection on the battery terminals on your vehicle will compromise this test.

Put a voltmeter on the battery before cranking. What's the voltage?

Leave the meter on the battery while cranking. What's the voltage?

When the engine won't crank anymore: What's the voltage?


Get some data and we'll solve the problem.