Starting problems. New starter, bendix, battery

[Roscoe]

What I'd probably do.... check voltage drop at various points along the starter circuit. Maybe jump from a known good battery right to the starter, if that doesn't spin the starter like it should you have starter mechanical issues or some other mechanical issues. If it does spin like it should when jumped then it's a starter system issue. Could be the starter solenoid, could be a bad connection, could need larger wiring, bad ground. Diagnose and fix. This looks like a good video on the subject....