Working on memory- I believe that on the starter- the 1 threaded stud had the battery cable & feed line for the charging/power supply for the unit, the other stud had the feed line for the starter brushes. The slip on terminal was the feed line to energize the solnoid.

I remember 1 relay- the horn relay, in the wiring. There were no relays in the starter circuit. The starter circuit was quite simple- fron the ignition switch, to the nuetral switch, to the starter solnoid.

If you have no power at the solnoid, check the igntion switch, then the nuetral switch, then the connector on the left side of the cowl- that used to get all corroded- at some point I used to just cut it out & hardwire the wires together.