X7 phenom odd issue after rebuild?

[Myrkul]

I'd actually have to work if I was an engineer instead of just sending a few emails and tinkering with paintball guns all day....

[BrickHaus]

I was gonna say, if you cant figure it out, its junk yo...

Btw you are in the wrong industry. You shoulda been an engineer. Lmao

[Myrkul]

Never mind, the center valve spacer "O" Ring had a nic in it problem solved, it's running just fine now.

[Myrkul]

Just did a full rebuild on old X7 phenom for a buddy, and it has this odd issue where it will shoot, then there is a delayed "puff" of air inside the gun a second after the shot. If you try to pull the trigger before the "puff" Nothing happens. If you pull the trigger after the puff it fires normally. Regulator seems to be holding pressure fine and the velocity adjustment works.

Any ideas on what I did wrong?