I was just going to say the same, there is only pressure at the transfer port/barrel joint after you pull the trigger and until the pellet leaves the barrel. The barrel is either moving the cylinder or the block and causing the leak which will be somewhere between the cylinder/reg/block.
Probably just a hardened o ring that no longer flexes to maintain a seal.
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.