Tuning AirForce Talon SS tank won’t fill

I got my Talon SS out after a year in the safe and the pressure had dropped from 3K to 2500. The gauge doesn’t seem to work right now and while filling with Hill Pump at about 2700psi it suddenly lost air and pressure down to 1000psi. Pressures were from the gauge on Hill Pump. Now the spin lock tank won’t take air beyond 1000 psi then it just leaks out. 


Any ideas or thoughts are appreciated. The tank is 3 years old and the Hill Pump is 1 year old.


Thanks from a pcp shooter with not much experience. 
 
Rebuild while you have the tank empty.
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Tony has very good male foster fittings. He has O ring kits for the valve and 90D O rings for the breach in the kit. There is a O ring under the brass piece in the picture that is a common leaker and I would replace it while you have the tank empty. I have three Condors and all of them needed those O rings and foster fittings fixed after a few years. Tony also has gauges that are dead on, not like the junk gauges that come with the guns.