my 73,intermittently turning key will not engage starter.new starter.if i jump terminal on starter with screw driver,even just to spin starter motor without solenoid engaging,i can go back and turn starter motor with key.sometimes it seems that if i push on ignition switch connector under dash it will start.ive ordered a new switch,old one looked okay.any ideas?

While it likely could be be the solenoid dying, consider replacing both the ground strap from the transmission to the body as well as the ground from the battery to the body. After 40 years these things build up a lot of corrosion and resistance and can make adequate passage of electricity problematic. I replaced both of mine and it made a HUGE difference.

I have also had a dying starter, which I believe was the solenoid which actually went bad. Exact same symptoms you mentioned. The solenoids and starters can be cleaned and rebuilt I believe. Consider having it rebuilt and replace the grounds. It'll give you piece of mind.

That's at least where I would start if you've already replaced the ignition switch.

the starter and solenoid are new(3 months old).trans ground starp was just cleaned.ill check ground on battery.

i havent replaced ignition switch,have one on order.just wondering why jumping terminals on starter motor would make switch work again?

Sorry, did not read that in your original post without the spaces after periods. Electricity and switches are funny things and keep in mind that they're all 40 years old now. Can't explain to you why it works once you jump it, but I think you're going down the right path with a new switch. Good luck.