FX Panthera. Replaced Oring. Now low Power

So my Panthera started to leak right below the barrel at the black nut with two holes in it. Took it apart, replaced an oring in that nut or cap, put it all back together, no leaks. This was for the valve rod. Now the gun has low energy when shot. Does not seem to be getting air from plenum. The air gauge does not move at all at the shot. Anyone have any ideas. This is a 600mm 22.