Troubleshoot 1377

[Acutus]

Hey all! Decided to get out my old 1377 and need some help troubleshooting. Basically air doesn't seem to enter the valve. Whenever I pull the trigger its the same as if I hadn't pumped at all. There is resistance when I pump so I think the piston is ok. I also replaced the O-ring on the outside of the valve.
Any ideas or things to try?
Thanks!

[Airspace]

Sounds like Skeeter nailed it. Is it a bolt or a rear cocker?

[Acutus]

Wow! Thanks for the quick replies!
It is a bolt version not a rearcock.
Same thing happens if I cock the gun first.
I think I hear the gasps but am going to try lubing it some to make sure.

Feels like it has compression about 3/4 of the stroke then it breaks. The air has to be going somewhere. Would I hear it if it passing the cup at that point?

[Acutus]

Got it! It was the O-ring between the two halves of the valve!

Th!nks for y'alls help!