Wow, looks great for its age Bruce! Nice!
Unfortunately, without sending your knife in to Spyderco, you're probably going to be SOL on disassembly due to the pinned construction. If compressed air alone isn't working for you, I'd recommend cleaning your knife with hot soapy water (dish soap works great), using a small brush, toothpick, qtip, etc., to loosen any debris around the pivot, and then blowing/drying it out thoroughly with compressed air. If that doesn't work, it may be worth it to you to send it in to Spyderco to see if they can open it up and get it back to 100% for you.
For me personally, a little grit in the pivot of a user isn't a major concern.. I've gotten sand in pivots before and it usually works its way out on its own with time or minimal cleaning..just keep on using it! Oh, and welcome to the forum!
..well, that escalated quickly..