Ignition switch issue

After much trial and error I have traced a problem back to the ignition switch. My car (70 S) starts and runs fine--and then completely died at random times. I replaced fuel pump relay etc etc. No change. Today when warming up the car I accidently barely nudged the ignition key--everything went off. I now assume it could do that by itself when hitting a bump or just to be ornery. Which parts do I need to replace or repair?? I think it is original as original key works it.

If you investigate the back of the switch you'll probably find that the two screws holding the electrical portion to the aluminum housing are loose, the bottom is easily gotten,,,,the top not so much, but see if those are loose. If not the electrical portion is separate and replaceable.

Thanks Ed.

Disconnect the battery before trying to tighten the screws.