Ken,

Connect a wire to the solonoid screw that connects to the wire to the key switch. When turning the key doesn't work, touch this wire to the + battery terminal.

If this gets the starter to work every time, the starter and solonoid are OK and the problem is either the key switch or something between the solonoid and the key switch.

You should get a wiring diagram of your model so you can see just what is between the key switch and the solonoid.

P E H