Check sudco.com -- you can almost piecemeal order the whole carb, part by part from them. They have the little o-rings, tiny washers, and yes even the fuel screw spring. Buy like 5 or 6 of each. Then when you drop them, after looking for them (and not finding them) after about 5 minutes, just go to your box and grab another. They'ree very reasonable price-wise, but I think they only take phone orders as of right now.
You have to navigate the web site on your own - I wasn't able to copy and paste any URL's, as the same address appears in the window for every page you go to (weird).
You'll need items 33, 34 and 35 (coded below):
33. Pilot Screw, Coil Spring
021-041 1290-812-2001 all
34. Pilot Screw, O-Ring
021-043 W9351-11028 all
35. Pilot Screw Washer
021-045 0301-803-2000 all
Here's the drawing to go along with the part numbers above:
http://www.putfile.com/pic.php?img=4284292
-matt