My symptoms were: turn the key, and hear a click. And to determine if the contacts were loose you tap on the starter with something substantial like the lug wrench from the trunk. If the car starts right up after tapping on it, try this fix.
starter opened up, to reveal nasty worn contacts.

New contacts 2.49 at local auto store ( NOT Schucks or pep boyeez) Your store like mine might not have a book to tell you whether they have some that will fit, just go down there and compare. This is really generic import stuff.

I decided to not replace the plunger, it looked fine. The one contact was very scored from being twisted on installation, the other contact looks good too but at 1.25 per why not replace both. THis picture shows both old contacts and the plunger.

There. A fixed starter for under $3.
The starter contact failed because I was taking the starter on and off so many times and every time I tightened the nut that holds the cable that leads to the battery it would twist the contact inside the starter. Be aware if you are constantly swapping motors or trannys...