Pneumatic Tandems

I'm having an issue with the locking pins retracting on my trailer, they are pneumatic operated. When I push the pin in there is a major leak from the black pin pushed or pulled to operate the locking pins. I sprayed liquid wrench and with a little extra uhmf they retracted, I went to set so I'm not riding around with my tandems all the way back...so immediate crisis resolved.

With that said, looking underneath there is a short bar that runs down the center located above the tandems, then this is pulled or pushed does it engage or disengage the pins? I'm looking for a way to manually release and engage the pins, seen how it is done on older trailers with a tool, however how to do this with the pneumatic release baffles me....yes I could go to a garage, however stuck at a flying J on a 34hr reset, would rather work the issue, learn and understand (now no air leaking or pressure when the knob is engaged or disengaged).
Thanks in advance...