Couple of things you could try with the console.
1. Type "stacey->enable" into the console. This will fix it if he has been disabled somehow.
2. Type in "ra" or "resetactors". This will reposition ALL NPC's in the world to their original positions. Dont worry, this wont reset dead characters or anything but it can make characters that you have escorted somewhere return to their original position (although the escort quest wont start again or anything weird). This could fix the problem if Jim has bugged out through the walls or something.
3. Type "player->placeatpc "stacey" 1, 20, 1" into console. Should create a whole new Stacey infront of you for your enjyment!