I would take a good look at the ignition switch or the neutral safety switch. My "68" 3000 and "69" 4000 have to be in neutral, both levers before it will turn over. The 3000 netural safety switch is going bad, I have to shuffle the gears around a bunch and back to netural sometimes before it will start. There's really not much left for you to swap out for her to get go'n again.
It's running. One of the first things I did was look at the safety switch. The selonoid I bought was bad. That was the first thing. We rried to jump direct to starter, nothing. Pulled new starter and parts fell out everywhere. Since it was new, I was not thinking about that.Sticker on selonoid and starter said, "made in china". Did not research parts for OEM or good reliability. The tractor parts supplier sells junk. Lesson learned. My neighbor sent me to a good supplier.
Thanks for all the tips and ideas.