Starter making screeching type noises. What could it be?

For the past few months on my dads 2000 4runner, there is this screeching type noise after the truck has been started and immediately goes away. Lately it's gotten worse and is making this noise when it's cranking over. The starter isn't making any clicking noises and has approx 210,000 miles on it. Noise goes away right away it starts.

What do you think it is? Does it just need the contacts and plunger replaced or something else like the whole starter?

 

starter is goin out... new one

 

The starter is not disengaging quick enough and is getting driven by the engine. Remove the starter, clean, and grease the bendix. Or, the bearings are toast... time to rebuild then.

 

What's the cheapest way to go. I looked around and can get a rebuilt denso starter for about $70 but you don't know what's been replaced.