Well, it kind of depends on your intentions for the knife. A hard user, an occasional user, a display knife.
If you are going to give the knife hard field use, I would re-peen the pin. Look close in bright light, and you will see a brass pin (usually finished flush with the guard). Use a flat punch the size of the pin or slightly smaller. Then refinish the brass flush.
For light occasional use, I'd just add a drop of crazy glue to take up the slack.
For a display, the looseness won't matter.
At any rate, congrats on acquiring a good Schrade knife! Try as they did, I don't think the design has ever been improved upon!
Codger
PS- This is your forum too! Don't be a stranger!