Older Disco showing full tank just gives a spring noise when fired. No air. Pellet does not even make it out of the barrel. Really love this rifle and would love to get it operating again.
You may bleed a discovery through the pressure relief on your fill unit. Hook up & fill un till that "click" say's the check vale is open ( you'll know right then if it's overfilled) close fill tank/stop pumping and SLOWLY open you fill unit bleed valve, stop as soon as air starts coming out and leave it a few minutes or until psi is where you want it.
De Gas tool is a number 10 machine screw pretty sure it was fine thread. Any hardware store, I'm in the boonies so I could walk into store with gun. Crosman gauges suck, I had a frozen guage and a leaked out gun that was the result of a mistaken 3000 psi fill. Normand of the old DiscosRus talked me thru it. I still have Discos he rebuilt 7 years ago, and working flawlessly.
Degasser came. Released pressure, pumped back up and voila, she's back. Now I have 2 Discos because when my Disco stopped working I immediately ordered a new one because it is my wife's go to squirrel eliminator. Thanks to all the member advice.