Chevrolet Repair: Starter motor problem, chevy van g20, starter solenoid

Question
I have a 92 chevy van, G20, 3.5 V6. When I turn the key the starter motor only engages for a second and then just spins. Out of 20 tries it will do that about half the time and the rest it just spins and doesn't engage at all.if I'm lucky it will turn over enough to start. I've just replaced the starter solenoid and it didn't change anything.
      Thank you for your time, David  

Answer
Hi David,
That little pivot arm that pulls the bendix in may be broken.
It is also possible that you have low voltage at the starter, which you can measure while cranking. But if the solenoid is maintaining contact and spinning the starter, I would check that pivot yoke, and probably stick a new bendix on while you have it apart.
Van