Replace the Coil head.
Are you using generic heads? Some have weak or enlarged bottom grommets and they swell out when you attach the PT to the device.
Air passes through the Small Side Holes in the 510 connection, down to the Hollow Center Pin and up through the
tank.
If Pinched, no air will pass the Grommet.
Testing Off the
tank can give a false positive for correct function since the center pin is open to receive air.
If the Head is the problem, it can still be used in the Mini.