Battery post on solenoid spins

[4thgencreamsicle]

Newbie here so go easy. Also, I searched the forums but definitely may have missed something since there are soooooo many starter issues threads.

While doing other work on the truck (‘69 c10) I disconnected the battery lead from the starter solenoid (was barely finger tight) and realized that when reinstalling the cable that the battery post on the solenoid spins in place. I haven’t had any starting issues (yet). I have looked at diagrams on this forum but can’t get a good idea of what is going on. Is there a nut on the inside that would be loose causing this issue or is something busted inside that isn’t gonna be helped by a rebuild kit? An I missing something completely obvious?

I’m asking so I know whether or not this will be a rebuild the solenoid situation or just buy a new one. I am learning all this as I go, guessing it’s time to learn about starters.