[BirdDog]

Sounds like your Bendix gear isn't retracting fast enough (most likely gummed up).

I'd watch the video that jrgill posted a link to, and do what the guy in the video did (took it apart, cleaned it, re-lubed and then put it back together).

My thoughts go like this:

If the solenoid was failing it would grind at the start because the solenoid is an electromagnet. If it was failing it wouldn't have the power to push the Bendix out.

Since the noise you are hearing is at the end of the start, it means the Bendix isn't being retracted quickly enough (it probably sounds like a terrifying grinding noise). Either the spring that pulls it back is broken (could happen, but very unlikely) or something is preventing it from coming back fast enough (like a gummed up shaft).

Easy solution is to just replace the starter.

The less expensive (practically free) solution is do what's in the video.