I am inclinded to go with the 135PSI answer.
Suggestion blead it down Remove the coupler. Install a quarter turn air valve (Get those any big box home improvement store and most hardwares) and that way you can cut off air to the coupler. Then you can push in lock down and apply pressure by opening the valve.
IF in fact it's frozen While it's off the rig. A small rod like tool into the center and wack it. NOTE as someone said 5-10 bucks to replace.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times