Originally Posted by -=TigerPB=-
It's my guess that you'll want parts nos. 9 and 28 (power tube o-ring, transfer tube o-ring)
That damage on the bolt is normal--the ball detent is steel and damages the bolt. You could replace the ball detent with some sort of nylon bead or plastic ball bearing. That's what most people do. Try smallparts.com for the bearing. Also, that is not the proper bolt o-ring. The bolt o-ring is available on the page i gave you.
The damage to the bolt usually isn't a problem, but in your case it looks like it's starting to form a sharp lip on the forward edge of the bolt that contacts the paintball. You might want to grind or sand that down until it's nice and smooth again.
Also, for some reason Stingrays like automatic transmission fluid. Back in the WARPIG days, Bill Mills and "Sid" used to recommend putting a few drops of ATF down the ASA, screwing the tank on, and running that through the valve. It probably causes the cupseal to swell and/or fills in some of the pores that could leak. You might want to try that first and see if it fixes the down-the-barrel leak.