[Gravy]

Sad thing is, i use to know this, but i believe the solenoid engages the motor which spins the gear, AND pushes it out. I've have to look it up again, but if it's not sounding good, you can start by checking the conections to make sure there's no rust, and see if that helps. If not, pull it out and bring it to a local parts store, i know Pep Boys and O'reilleys both test them. And can let you know if it's bad or not.

Most of the time it's best to go with a remanufactured starter with a lifetime warranty, and just get dirty yourself. Save you a ton of money in the long run.