RobWNY - I don't have an air spring "pin box" but have B&W 5th wheel. Are the jaws not closing because the pin is too far out of "plumb" (vertical "level") with the jaws?
Does the air spring in the pin box force it nose down? This is an unnatural angle for a pin and 5th wheel to try to hitch.
If yes then you need to adjust whatever so the upper 5th (pin and plate) are in a reasonably close plane with your 5th wheel ("hitch"), or tilt the 5th wheel front down a bit with a bungee or something so it planes to the pin box as you back in. Don't strap it solid let it rock.
Also making sure you are backed in with a bit of pressure on the front of the pin allows the jaws to close freely. Set some weight on the truck and push on the trailer gently.
As you know the B&W does not need to be slammed into the pin to lock up. The lever & pin locks it.