Starter issues again!

^^^^^ Looks like the red part is the electric magnet, that is energized by power coming in from the single wire from the start relay.

When that red magnet is energized it pulls the solenoid back to complete the power circuit to spin the armature.

If the wire you soldered is broken, no magnet, no maget no spinning starter.

Lol . . Sure you have that all figured out by now.