I have had starting trouble with my 1972 for a long time. I have tried several things, some things 2 and 3 times, but still cannot get the ignition to work.
A little history - About 2-3 years ago the car would sometimes just not start using the ignition switch. I could push start the car or short across the solenoid and get it to start. The car would eventually start using the ignition switch. The timing was random and didn't have anything to do with the car being hot or cold. Sometimes after not starting I could get it to start just a few minutes later and other times it would start right up after sitting for days.
Things that I have done - swaped the starter with another used starter but it still did the same thing. I changed the white ignition switch about a year ago. I thought that that had fixed the problem, but after a couple of months it started doing the same thing. I cleaned the battery posts, clamps, all terminals that connect to the battery terminals. I've cleanded the ground strap that connects to the body near the battery, and the body to tranny ground strap. I've cleaned the terminals that connect to the solenoid. The battery is not great but I have a charger/start booster that i use also.
Any suggestions on what to try next???