It's an old SID. Air shock, so you'll very likely need new o-rings/seals inside, and if it's that old, may need bushings as well.

Doable, but you're into some work and money to find some of the stuff. Plus, those forks are wet noodle flexy as well from the start.

IMO you'd do better off to just ride it and save up for a new fork or bike all together.