The clicking noise is a solenoid that's on top of your starter that engages the starter to the motor. When you turn the key the solenoid pull on a lever and that pushes the starter gear into the flywheel.
When the solenoid is at full travel the back side of it hits a copper disk and conects the battery to the starter motor. It then turn over the engine.
Two things cause the starter to click. One is a dead/low battery. The solenoid with operate, ingage the gear but when the motor try to pull power from the battery there's not enough voltage to hold in the solenoid. So it snaps back (there's a spring holding the starter gear out of the flywheel). So now there's voltage enough to pull the solenoid again. This goes over and over so you get that "click, click, click...
The second is a bad flywheel. If the teath of the starter doesn't go into the flywheel, then the copper disc will never make contact and turn over the starter motor and it will just click once. Some times the flywheel is worn and eventhough the teeth dont mesh the disc make contact and the starter motor rotates without being ingaged to the engine.
I'm beting you have a bad spot on the flywheel.
(p.s. In the olden day you had to shim the starters. And if you didn't shim them right you would get the same results. My tracker bolts on to the side so there is no way of shiming it. I don't know about sammies)