My Daisy 851 was leaking so I bought a rebuild kit for the 853. everything looked pretty much the same but now after reassembling it, the first shot is quite weak, but if I cock it again (not repump) then it will shoot again a lot more strongly, and sometimes it will even do this a third time on the same pump. I have not tried a bb or pellet in there because I'm afraid that first shot might be too weak to shoot it out. IT's supposed to release all it's air on the first shot so this is really weird. what have I done wrong?