[R Bedell]

I see possible three conditions here.

(A) You have a bad ground somewhere.
(B) You have a bad Starter Solenoid
(C) You have a bad Starter Drive (Bendix).

Test A:
With a VOM or DVM, check the resistance connection between the Battery Negative ( - ) terminal and the case (or body) of the starter solenoid. You should have near zero ohms resistance. If not, look for bad grounding connection (wire). If you do....then to test B.

Test B:
With the same meter, select VDC scale (say 20V). Place the black meter lead on the starter solenoid case or body,. and the red lead on the small solenoid terminal. Turn the key to "start" position and you should see 12V at the solenoid.. If not, then something in the start circuit has failed (safety switch, ignition switch, etc).

Test C:

If you have 12VDC at the solenoid and it still won't engage, then take the Meter and check the resistance of the solenoid coil itself. Meter on Ohms scale, check between solenoid case and the small terminal (wire removed from small terminal). You should see between 5-100 ohms. If not, the solenoid is TOAST (open coil).

Test D:

If all the above check out normal, then with the wires to the two large terminals removed, take the Meter on Ohms Scale, and check for resistance of these two terminals. Not engergized, you will have NO ohms (infinity). When turning the Ignition Switch to the start position and energizing the solenoid, there should be zero ohms resistance. If not, the solenoid is TOAST (bad contacts).

Check this out and advise.