1969 Javelin Starter Motor Problems

Your starter solenoid has a provision to activate when transmission is in park or neutral. If your neutral safety switch is bad, the solenoid won't engage when started.

Also if the S terminal of the solenoid has a broken wire on the harness, it will not receive power from the ignition switch to engage.

Your starter seems to get proper ground as jumping to the starter cable cranks the engine. So no ground issues I forsee with your starter grounding to the engine block and trannie.

Though, some forget to add the wee ground cable that connects at the cross member and to the engine block at the mounting bracket above the motor mount, it should be installed as it can lead to many issues with various electricals.

Looking at your connections will tell you nothing. You should google vpltage drop test. In short it sounds like you have a problem on the ground side of the circuit. With out testing anything you can use jumper cables and bypass the ground side by hooking one side to the starter housing and the other end to the negative cable at the battery. Starter should work now if problem is on ground side unless the problem is on the connection from battery cable to post. If you want to check the integrity of connections you can turn headlights on. Then using a DVOM probe the negative post of battery one probe the terminal of cable end. with DVOM on DC volt scale. If DVOM reads more than .02 of volt connection is not good, the higher the reading the worse the connection. This can be done at each connection, post to terminal, terminal to cable, cable to terminal at block, terminal to block. The circuit you are looking at must have current flowing threw it to work, thats why the headlights are on. The problem you have will have way more than .02 volt drop to keep a starter to work but this should give you an idea.I had a customer at work yell at me for using this to check connections on his no start jeep. He had "checked" it already and knew it just needed a starter and I was just running up the bill. His batter cables had the replacement bolt on ends. His positive cable while being perfectly clean post to terminal had an 8 volt drop terminal to cable. After cleaning this connection it started and ran. Hope this makes sense.

I find that a lot of old cables have internal corrosion, if you bend them, they "crunch"........they will cause plenty of problems.

Thanks for all the help. The problem ended up being my negative battery cable not being properly grounded to my block.