The small o ring goes onto the end of the bolt. I had the same problem when I resealed my Sears model 126/ Crosman 1400. You need to tear it back down, take the valve apart and clean it really good. The bottom part or where the air is pushed into the valve has to be spotless and polished. You most likely have some trash or residue in there. I used lacquer thinner and really fine steel wool to clean up mine. Remove all the parts and check the plastic check valve for scratches. A loop is nice to have so you can see trouble spots up close. Be sure to wash it out really well with pure alcohol.Bryan