Hi , I am trying to install new seals into a Benjamin 2600 I recently acquired and when I load in the co2 it just empties right out. My question is ..after removing the lock ring-washer-piercing rod-spring-exhaust valve/rod- there is a black o-ring around the base inside of the chamber..I had to dig out the old original and now have (what I believe to be the correct ) black rubber o-ring just pressed into a trough in place...1st rebuilt it with a white hard plastic exhaust rod/seal and 'poof''gas goes away..dis-assembled and used an exhaust rod/seal from the earlier Benjamin series that is brass with the rubber sealing surface laying against the gas valve opening..re-assembled and...'poof' gas just runs right out----- question----- is there some mechanism that is supposed to be holding the larger black o-ring inside the gas housing in place , it seems to be just sitting in a race with no reason and can -lift-shift-move-etc..after three times I am needing input please..thanks , Randy