Snowpeak M25 Not arming to shoot!

I do not own a M25, had to look up what it is, but I have three P35s (which I love). I think you are saying it cocks and holds air in the tube but when you pull the trigger it won't push a pellet out? That sounds like the regulator. I have not taken my P35s apart to get the regulator out but it is visible in the far end of the airtube and I've changed the setting in my 25 caliber. I've seen tear down youtubes for the P15. They are pretty useful for my P35s and may be too for your M25. It's been awhile since I saw them but I think you push pins out to get the regulator out. After taking all the pressurized air out of course. If I understand your issue I think either the regulator has taken itself apart or there is some debris in it.